# Fuel Grade



## 87 (Nov 2, 2010)

I've heard a lot of debate over what kind of fuel the 1.4L T should use (regular or premium) and hoping to get some opinions from you guys and gals. I've heard that premium causes less detonation (whatever the heck that means) and is easier on the engine, increasing service life. Also if I was to use premium gasoline which is more expensive, will the cost justify the means due to the fuel economy evening it out?


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## shawn672 (Oct 31, 2010)

using a higher octane won't net you a better fuel mileage. at best you might gain some hp but its uncertain at this point. until someone gets one on a dyno we'll probably never know


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## cruze-control (Jul 23, 2010)

you dont need a dyno to know if the premium fuel will make any difference. it will. its been discussed here before. i have a lot of experience with turbo cars and turbochargers in general and ive used regular on them before. never had any good results. car ran like crap, excessive knocking in the motor, and ridiculous amount of power loss. i wouldnt suggest trying it as i have lost one motor already to detonation. heres a really good explanation of what detonation is. 

Detonation of Motor Fuels definition of Detonation of Motor Fuels in the Free Online Encyclopedia.


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## shawn672 (Oct 31, 2010)

I understand what detonation is and how higher octanes work. GM is recommending 87 octane on all cruze's. I understand higher octane might be better, but if you engine blows under 100k GM replaces it for free..


Here is an email response I've received from their engineers:


> Dear Mr. Miller,
> 
> Thank you for contacting Chevrolet and for your interest in the 2011 Cruze! We appreciate the time you have taken to write us.
> 
> We are unable to provide exact measurements for the octane ratings you mentioned in your response email. The vehicle will run more efficiently with a higher octane level however this will not provide you with added power. A higher level of octane will last longer and is generally cleaner than your lower level octane. The Cruzes 1.4 ECOTEC turbo engine is equipped to run on 87 octane and we would not recommend anything higher than 91 octane. For further details please consult your local dealer for technical assistance.


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## cruze-control (Jul 23, 2010)

shawn672 said:


> I understand what detonation is and how higher octanes work. GM is recommending 87 octane on all cruze's. I understand higher octane might be better, but if you engine blows under 100k GM replaces it for free..
> 
> 
> Here is an email response I've received from their engineers:


let me explain their email. see how they say the cruze is "equipped" to run on 87 octane. they use the word equipped instead of recommend because the car has a knock sensor which will dial back the timing of the motor when it detects low grade fuel. you said they are recommending 87 octane which doesnt state that in the email they sent to you. most of the older cars actually go into limp mode when they detect low grade fuel which basically just gives you enough power from your engine to "limp" home. also running anything higher than 91 is pointless for such a small turbo. now if you upgrade your turbo to something like a t67 then using a higher octane will make a difference.

yes they will replace the motor but do you think its worth all the hassle and losing the car for whatever the amount of time it takes them to diagnose the problem and put in a new motor or fix your old one. imagine if you were merging into the highway and suddenly experience detonation and the motor retards the timing which slows down the car. that can be a fatal problem if there is a car catching up to you. not trying to be a know it all but i have years of experience with modifying and tuning cars.


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## shawn672 (Oct 31, 2010)

You probably have more experience than I do so I'll deflect to you. Do you have a cruze yet? Did you notice any performance increase when switching to a higher octane? What did/do you use?


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## 87 (Nov 2, 2010)

Great posts. I think I'll try out the 89 or 91. I do have one more question that I don't think I've found on here yet... can you mix different fuel grades or should you run your tank to just about empty before filling it up with a different grade of fuel?


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## cruze-control (Jul 23, 2010)

shawn672 said:


> You probably have more experience than I do so I'll deflect to you. Do you have a cruze yet? Did you notice any performance increase when switching to a higher octane? What did/do you use?


don't have the cruze yet. probably going to get it next year when they try to clear out the old models. so i can pick it up cheap. i did find some first hand account from owners that they did notice better throttle response when they filled it up with 91 after they got it from the dealership.



moobox said:


> Great posts. I think I'll try out the 89 or 91. I do have one more question that I don't think I've found on here yet... can you mix different fuel grades or should you run your tank to just about empty before filling it up with a different grade of fuel?


yes you can mix different fuel grades. try avoiding running the tank empty on the turbo motor. running out of fuel while accelerating on a turbo motor is 10x worse than using low grade fuel as you will have increased air pressure due to the boost but then no combustion because of the lack of fuel. also dont try testing 89 and 91 until you fully break in the motor. i would suggest driving it on 91 for the first 500-1000 miles than do the test.


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## 70AARCUDA (Nov 14, 2010)

...interestingly, the USA manual states 87 octane, but, seemingly, some overseas models state 91 octane.

...anybody know *why* the difference--possibly, fuel grade or quality?


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## CruzeChick (Nov 13, 2010)

So after reading this discussion, I should put 91 in my cruze when I pick it up???


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## 70AARCUDA (Nov 14, 2010)

...use the octane that _your_ Owners Manual states.


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## shawn672 (Oct 31, 2010)

I've now gone through 2 tanks of 87 and 1 tank of 93. I did not really feel any difference?
If there is, it's minor. I need to see some numbers showing the higher octane actually helps this car at all. Until then I'm saving $5 and using 87...


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## cruze-control (Jul 23, 2010)

70AARCUDA said:


> ...interestingly, the USA manual states 87 octane, but, seemingly, some overseas models state 91 octane.
> 
> ...anybody know *why* the difference--possibly, fuel grade or quality?


the difference is not in the car nor the available fuel grade. its all about who they are selling the car too. they are trying to market this in north america as a really affordable sporty sedan. but they also know that recommending that consumers only use premium fuel in the cruze will deter a lot of people. remember the whole uproar about how the chevy volts were marketed to require premium fuel while everyone said they want it to use regular fuel. its the exact same scenario here. they dont want their high mpg and low budget sedan to look like a hypocrite by preaching savings but require more expensive fuel. 

thankfully this way of thinking is not as widespread in other parts of the world. which is why on their manual its says the "right" fuel to use. ask anyone who has worked with turbochargers and superchargers. they will all tell you why you need to put premium fuel in your turbo car.



CruzeChick said:


> So after reading this discussion, I should put 91 in my cruze when I pick it up???


yes you should.


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## 70AARCUDA (Nov 14, 2010)

...one has to wonder, however, *how* GM can warranty the engine on 89 octane, if, as you say, 91 octane is what *should* be used.

...sorry, I'm not buying it. Granted, using 91 octane might help you gain somewhat more HP when you're drag racing, pulling a heavy maximum capacity load, or climbing through mountains fully loaded, but it is probably not necessary for the 99.9% population who drive under "normal" conditions.

...if 91 octane was required, it would've been so stated in the Owners Manual, by the GM lawyers.


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## bpipe95 (Nov 1, 2010)

Gm relies on knock sensors to protect the engine. In most cases they will more than protect the engine. The few that don't can conveniently be pushed into the "abuse" file.


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## cruze-control (Jul 23, 2010)

70AARCUDA said:


> ...one has to wonder, however, *how* GM can warranty the engine on 89 octane, if, as you say, 91 octane is what *should* be used.
> 
> ...sorry, I'm not buying it. Granted, using 91 octane might help you gain somewhat more HP when you're drag racing, pulling a heavy maximum capacity load, or climbing through mountains fully loaded, but it is probably not necessary for the 99.9% population who drive under "normal" conditions.
> 
> ...if 91 octane was required, it would've been so stated in the Owners Manual, by the GM lawyers.


anyone who has enough experience with these kind of engines knows well enough that the need for a higher octane for daily driving is to prevent detonation under load. even if you dont floor the car detonation can still occur if the engine gets hot enough. like bpipe mentioned the knock sensor will retard the timing to compensate which should help protect the engine. but there will still be a few cars that the engine will go kaboom. for gm they are willing to take that hit since they will more likely lose more customers by them advertising that the cruze needs 91 octane compared to them just fixing premature engine failure when it does happen.

if you actually check one of the earlier post on this thread. there was a reply from a gm engineer and even the engineer said the same thing ive been saying. that you can use 87 octane but they recommend 91 octane.


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## ChevyMgr (Oct 27, 2010)

cruze-control said:


> if you actually check one of the earlier post on this thread. there was a reply from a gm engineer and even the engineer said the same thing ive been saying. that you can use 87 octane but they recommend 91 octane.


The email states it is not recommended to use any octane above 91, not that it recommends 91.

From the owners manual:

*Recommended Fuel*

Use regular unleaded gasoline with a posted octane rating of 87 or higher. If the octane rating is less than 87, an audible knocking noise, commonly referred to as spark knock, might be heard when driving. If this occurs, use a gasoline rated at 87 octane or higher as soon as possible. If heavy knocking is heard when using gasoline rated at 87 octane or higher, the engine needs service.
-----------------------

As cruze-control stated, conventional wisdom with a turbo has always been to use premium fuel. GM deems this to not be necessary for this engine.

You can use premium if it gives you peace of mind and you don't mind the 20¢ per gallon more coming out of your pocket, but GM states you don't have to. They stand behind that with their power train warranty.


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## MikeyCruze (Oct 28, 2010)

Based on the emails from Chevy and post by ChevyMgr I will stick with 87 octane in mine and keep some of that extra money in my pocket. It doesn't bug me at all knowing I could go to a higher level. If Chevy says 87 is perfectly safe and good, I will stick with that.


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## 70AARCUDA (Nov 14, 2010)

...my personnal policy: 87 octane for all 'normal' driving and 91 octane if/when driving under 'loaded' conditions, ie: heavy/full weight load, or climbing through mountains, etc.


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## Cruzer (Oct 18, 2010)

If the manual says 87, I am going with that.


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## motorhedfred (Nov 13, 2010)

Octane requirement is effected by lots of things. Boost certainly plays a big part, but so does ambient temps, coolant temp, oil temp, humidity, compression ratio....ect.

Worst case scenario...lots of boost, extremely low humidity, high air temperature, heavily loaded, coolant temps near boiling. All these things increase octane requirements, you might need an octane of 110 or more in those conditions. Cold humid weather. lightly loaded.....you might only really need 80 octane if it were availible. 

The car manufacturers err on the side of caution. It would be interesting to know what they have the peak boost set at.

MHF


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## 70AARCUDA (Nov 14, 2010)

...regarding "peak boost" -- there are people now who are attempting to learn if that info can be read-out over the OBD-II port using one of the aftermarket gauges (such as ScanGauge or UltraGauge, etc.).

...first, we have to know if such info is "GM_Proprietary" and as such wouldn't be made available to the general public (ie: a general code).

...then, because we *still* want to know, it becomes a 'detective' game of literally searching through all the available engine control unit (ECU) codes to see if the data is available, but unlisted.

...finally, using the programability function of a ScanGauge, one could code it to search for and read the illusive info...and display it on the gauge readout.

...nothing is _impossible_, just sometimes it's rather _improbable_ (ha,ha).


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## shawn672 (Oct 31, 2010)

70AARCUDA said:


> ...regarding "peak boost" -- there are people now who are attempting to learn if that info can be read-out over the OBD-II port using one of the aftermarket gauges (such as ScanGauge or UltraGauge, etc.).
> 
> ...first, we have to know if such info is "GM_Proprietary" and as such wouldn't be made available to the general public (ie: a general code).
> 
> ...


 


> Originally Posted by VinceTrifecta
> Well, just got done doing some logging. There's most definitely room for improvement.
> Here's some numbers from the stock tune:
> Commanded AFR @ WOT (PE Mode): 10.3:1
> ...


The thermostat is electronically controlled to be at 220degrees F all the time, which is terrible for performance.


This is from a company called Trifecta who played a huge part in Cobalt ECU tuning and will do the same for the Cruze hopefully (they just bought a LTZ and are using it as a test mule)


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## cruze-control (Jul 23, 2010)

thanks for that info. im really surprised theyre running 16 psi on stock boost. most other cars ive dealt with usually run 7-10psi on stock boost. that afr at wot looks really rich.


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## shawn672 (Oct 31, 2010)

it is really rich, and the turbo is fairly maxed out i believe. i can see a bigger turbo upgrade coming soon aftermarket


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## Cruzzer (Dec 13, 2010)

Run 89 and be done with it


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## shawn672 (Oct 31, 2010)

Cruzzer said:


> Run 89 and be done with it


Well I'm still getting mixed answers from different people close to the matter.

However, I can FEEL a difference between 87 and 89. There is more acceleration hesitation with 87 and its not just placebo effect


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## sedanman (Dec 10, 2010)

shawn672 said:


> However, I can FEEL a difference between 87 and 89. There is more acceleration hesitation with 87 and its not just placebo effect
> 
> edit: I now have over 2k miles and have switched back and forth a few times, mostly 89 and then 3-4 tanks of 87


I concur 87 octane I'm getting hesitation upon acceleration, it is very noticeable. I mixed just under half a tank of 93 in there which averages out to 89 octane, and it runs much much better.


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## SilverCruzer (Nov 30, 2010)

Car engines are built for a specific octane. Lower octane is more flamible (contrary to what most people think). Years ago, the reason people would use higher octane in an older car to prevent knocks is for this reason: build up (some times lead) in the cylinders causing a smaller compression space meaning the piston was firing too early before the spark, thus causing a knock. Higher octane is less flamible meaning it would allow the piston to fully compress and not explode prematurely. Using 91 in a brand new Cruze means you are putting less flamible gas in the engine for which its designed. There is no mechanical reason for a knock, nor a reason to supress a knock.

Quesion for those claiming 89 is causing less hessitation: Are you driving 1.4 or 1.8?


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## sedanman (Dec 10, 2010)

SilverCruzer said:


> Car engines are built for a specific octane. Lower octane is more flamible (contrary to what most people think). Years ago, the reason people would use higher octane in an older car to prevent knocks is for this reason: build up (some times lead) in the cylinders causing a smaller compression space meaning the piston was firing too early before the spark, thus causing a knock. Higher octane is less flamible meaning it would allow the piston to fully compress and not explode prematurely. Using 91 in a brand new Cruze means you are putting less flamible gas in the engine for which its designed. There is no mechanical reason for a knock, nor a reason to supress a knock.
> 
> Quesion for those claiming 89 is causing less hessitation: Are you driving 1.4 or 1.8?


I think we are all well aware the lower the octane the faster the fuel burns.
I personally have the 1.4 turbo.
Question for you: Do you own or have ever driven a Cruze and tried 87 and then 89 or 91 octane fuel?


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## shawn672 (Oct 31, 2010)

sedanman said:


> I think we are all well aware the lower the octane the faster the fuel burns.
> I personally have the 1.4 turbo.
> Question for you: Do you own or have ever driven a Cruze and tried 87 and then 89 or 91 octane fuel?


1.4l also. If you try both 87 and 89, you'll feel the difference that we're talking about.

The 1.4 CAN run 87 because it has a knock sensor that retards timing, with 89 it's safer (you dont have to rely on that sensor) and more timing means slightly more power (less hesitation it seems)


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## sedanman (Dec 10, 2010)

shawn672 said:


> 1.4l also. If you try both 87 and 89, you'll feel the difference that we're talking about.
> 
> The 1.4 CAN run 87 because it has a knock sensor that retards timing, with 89 it's safer (you dont have to rely on that sensor) and more timing means slightly more power (less hesitation it seems)


I absolutely do feel it. I know the owner's manual says use 87 but it just doesn't run as well as 89.


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## shawn672 (Oct 31, 2010)

Well and thats the thing, I wrote to GM and they said the car CAN run 87, but do not run anything higher than 89. They would not give me a direct answer on what I SHOULD be running. It was very odd. 

I'm no sure how European octanes differ from US but in Europe they recommend 89...


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## sedanman (Dec 10, 2010)

Honestly I don't know what they are thinking telling everyone to use 87 with this much boost. Maybe they wrote the instructions for the LS normally aspirated engine and forgot about the 1.4 turbo or something.

You know what would be great? An indicator that tells you when or how often the knock sensor goes off. Or tell us the timing advance setting so we can see what the engine is doing at different octane ratings, loads and weather conditions.


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## bpipe95 (Nov 1, 2010)

sedanman said:


> Honestly I don't know what they are thinking telling everyone to use 87 with this much boost. Maybe they wrote the instructions for the LS normally aspirated engine and forgot about the 1.4 turbo or something.
> 
> You know what would be great? An indicator that tells you when or how often the knock sensor goes off. Or tell us the timing advance setting so we can see what the engine is doing at different octane ratings, loads and weather conditions.



They have many devices that will do just that.


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## SilverCruzer (Nov 30, 2010)

I am half way through a tank of 89 and don't notice a bit of difference in power or economy. As a matter of fact, it FEELS less, but I am giving the benefit if the doubt that it isn't.


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## 2011lt1 (Dec 13, 2010)

i had a long talk with vince from trifecta last week. very smart knowledgeable guy. really enjoyed our conversation. 

here is the deal, chevy tuned the car to run on 87 for reason previously stated and its why its so **** slow for an FI car. so in its stock form without any sort of tune, 87 OCT is just fine to run. you might notice its runs better with 89 OCT since it is a FI car. 

if you were to get some sort of tune like the one Vince from trifecta offers it will have to run on 91 OCT or it will knock regardless of knock sensors or anything else. 

cruise control is right about running 91 in FI cars, but that's is for a car tuned to run on it. like with the hondas and aftermarket turbos which are tuned for big horsepower number and have very high air to fuel ratios so u have to run 91 to avoid knocking also known as detonation. that is not the case with the cruze in its stock form it was not tuned for performance not power. it was tuned for 36 mpg on the high way bottom line


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## shawn672 (Oct 31, 2010)

2011lt1 said:


> i had a long talk with vince from trifecta last week. very smart knowledgeable guy. really enjoyed our conversation.
> 
> here is the deal, chevy tuned the car to run on 87 for reason previously stated and its why its so **** slow for an FI car. so in its stock form without any sort of tune, 87 OCT is just fine to run. you might notice its runs better with 89 OCT since it is a FI car.
> 
> ...


 
and this is exactly what we already speculated. Vince is a really smart guy too, glad you had a good talk with him


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## SilverCruzer (Nov 30, 2010)

sedanman said:


> I think we are all well aware the lower the octane the faster the fuel burns.
> I personally have the 1.4 turbo.
> Question for you: Do you own or have ever driven a Cruze and tried 87 and then 89 or 91 octane fuel?


Yes - Owned LT since October with 4,200 miles. I just completed a tank full of 89 with my usual driving. I did not notice any difference at all with power, shifting, or economy. I was actually hoping to be wrong about this.


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## sedanman (Dec 10, 2010)

Maybe the tankful of fuel from the dealership was old fuel, or contaminated with condensation, because it hesitated a lot upon acceleration until I put a new tank of fuel in. And I put in 91. Next fill up I'll put in 87 and see if it goes back to hesitating again or not.

BTW it is "slow" for an FI car because of the small displacement. 1.4 liters is a small engine. It is designed to be fuel efficient not a hot rod. I understand it may be designed to run on 87 but keep in mind the engine thermostat is set to 220 deg. F. unlike other cars that are set to 195 deg. F. That might cause the fuel to ignite a bit faster.


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## Targus (Jan 2, 2011)

Cruze ECU ignitin map tuned by gm retardet style. 
Due to retardet ignition map effect less gas emision. 
retardet tuned engine works with low grade gasoline.


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## shawn672 (Oct 31, 2010)

Targus said:


> Cruze ECU ignitin map tuned by gm retardet style.
> Due to retardet ignition map effect less gas emision.
> retardet tuned engine works with low grade gasoline.


in english please?


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## TSURacing (Jan 1, 2011)

Im not sure if he is insulting the powertrain programmers are merely commenting on spark timing.
No offense or nuthin, I'm just being a jerk.


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## cruzers (Dec 13, 2010)

Targus said:


> Cruze ECU ignitin map tuned by gm retardet style.
> Due to retardet ignition map effect less gas emision.
> retardet tuned engine works with low grade gasoline.



Side effects of a global car.


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## 2011lt1 (Dec 13, 2010)

sedanman said:


> Maybe the tankful of fuel from the dealership was old fuel, or contaminated with condensation, because it hesitated a lot upon acceleration until I put a new tank of fuel in. And I put in 91. Next fill up I'll put in 87 and see if it goes back to hesitating again or not.
> 
> BTW it is "slow" for an FI car because of the small displacement. 1.4 liters is a small engine. It is designed to be fuel efficient not a hot rod. I understand it may be designed to run on 87 but keep in mind the engine thermostat is set to 220 deg. F. unlike other cars that are set to 195 deg. F. That might cause the fuel to ignite a bit faster.



just because the motor is a small displacement engine does not determine why its slow. look at the number that Vince pulled from just a tune and nothing else out of the little 1.4l. his numbers are whp, so they are more inline with a 2002-2005 wrx at the crank and that is a 2.5l. so how is displacement the reason for it being slow? 

its slow because it was not tuned to be fast. my 1.8 integra is perfectly cable of making 250 whp on a totally stock engine with a simple stage one turbo kit, will it ever be a 500 ft lbs of torque without major engine overhaul? no of course not there is no replacement for displacement, however it is not fair to call it slow simply because of it displacement when it is indeed a FI car


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## LARRY01Z28 (Dec 4, 2010)

i cant wait to get that tune


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## shawn672 (Oct 31, 2010)

2011lt1 said:


> my 1.8 integra is perfectly cable of making 250 whp on a totally stock engine with a simple stage one turbo kit, will it ever be a 500 ft lbs of torque without major engine overhaul? no of course not there is no replacement for displacement, however it is not fair to call it slow simply because of it displacement when it is indeed a FI car


i know you were talking about your integra but just thought i'd add, because of the forged internals, the 1.4l ecotec will take anything you can throw at it.


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## LARRY01Z28 (Dec 4, 2010)

i cant wait for more aftermarket parts.


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## 70AARCUDA (Nov 14, 2010)

LARRY01Z28 said:


> I cant wait for more aftermarket parts.


...might want to wait until after the GM warranty _expires_ first (wink,wink)!


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## 2011lt1 (Dec 13, 2010)

shawn672 said:


> i know you were talking about your integra but just thought i'd add, because of the forged internals, the 1.4l ecotec will take anything you can throw at it.



oh i totally agree bro. the integra internals are only good for about 250 whp and they well explode. then you would need to upgrade to forged pistons


the cruze turbo already has that. and if this block is as strong as the 2.0l turbo block it will hole a 1000 whp with the right internals


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## Woodlands1 (Apr 12, 2012)

Whatever octane you decide to run in your car, do use tier one gasoline. Not all gasolines are created equal


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## got_boost (Sep 29, 2011)

Can't this thread just die already.

If you have a 1.4 use 91+.
If you have a tune use 91+.
If you have a stock 1.8 use 87.
Few dollars you save ain't worth the loss of power and timing.

/thread


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## JeffBazell (Jan 24, 2012)

2012 Eco AT. I am very sensitive to engine performance, just by ear and feel. I used 87 until about 2000 then went up to 91. Definite improvement. More responsive from a stop, much smoother idling, better mountain driving here where I live. I think I'm even getting a couple mpg's more on 91 but I'm happier on 91 then 87. Just my 2 cents. "Cruze-Contol" comments seem to be very helpful and he's knowledgable.


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## Holden Sri-V (Apr 20, 2012)

here in Aus, our premium is 98 octane and thats what i run my 1.4T on, haven't tried anything lower so i cant comment on performance improvements.


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## Higgs Boson (Mar 7, 2012)

i use 93 octane and it increased my top speed by 5 mph! on 87 I could go 82 and on 93 I got up to 87, I bet I could go even faster downhill. also my mileage wasn't as good as when I was going 55. does GM have an answer for this? i was promised 40 MPG at least and now I am mad.


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## Higgs Boson (Mar 7, 2012)

Holden Sri-V said:


> here in Aus, our premium is 98 octane and thats what i run my 1.4T on, haven't tried anything lower so i cant comment on performance improvements.


measured differently than in the USA. your 98 is our 93.

Octane rating - Wikipedia, the free encyclopedia


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## obermd (Mar 3, 2012)

Higgs Boson said:


> i use 93 octane and it increased my top speed by 5 mph! on 87 I could go 82 and on 93 I got up to 87, I bet I could go even faster downhill. also my mileage wasn't as good as when I was going 55. does GM have an answer for this? i was promised 40 MPG at least and now I am mad.


You may have transmission slippage. The Cruze will easily do 100+ mph on 87 octane. If your top speed is truely in the 80s, there is something wrong with your Cruze.


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## Higgs Boson (Mar 7, 2012)

obermd said:


> You may have transmission slippage. The Cruze will easily do 100+ mph on 87 octane. If your top speed is truely in the 80s, there is something wrong with your Cruze.


If you think something is wrong with my speedo-meter there is something wrong with your JOKE-meter!


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## sciphi (Aug 26, 2011)

Recall, the EPA fuel economy tests are done using 91 octane!

91 octane, no additives. That way it's standardized across all the cars tested. It's known as indolene. 

That might explain why the 1.4T seems to run better and get better fuel economy on premium. It was benchmarked on premium...


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## obermd (Mar 3, 2012)

Higgs Boson said:


> If you think something is wrong with my speedo-meter there is something wrong with your JOKE-meter!


I'm not saying your speedometer is misreading. What I'm saying is that both Road & Track and Car & Driver have run Cruzes (LTZ and ECO) at over 120 MPH. If your Cruze is topping out in the 80s, is has a major problem.


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## ErikBEggs (Aug 20, 2011)

sciphi said:


> Recall, the EPA fuel economy tests are done using 91 octane!
> 
> 91 octane, no additives. That way it's standardized across all the cars tested. It's known as indolene.
> 
> That might explain why the 1.4T seems to run better and get better fuel economy on premium. It was benchmarked on premium...


Run better yes, fuel economy... NO.


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## XtremeRevolution (Jan 19, 2012)

ErikBEggs said:


> Run better yes, fuel economy... NO.


???

We do know that the engine knocks, wich causes spark retard, which creates a much less efficient burn, which means you will get better fuel economy with premium than you will with regular, especially during hotter days.

Sent from my Bulletproof_Doubleshot using AutoGuide.Com Free App


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## obermd (Mar 3, 2012)

ErikBEggs said:


> Run better yes, fuel economy... NO.


As soon as your engine starts to knock, you lose fuel economy. Increasing the octane when you engine is knocking will improve your fuel economy. Increasing it when your engine isn't knocking won't. The question in the former is are you paying less per mile by increasing the octane to eliminate knocking. In the later case you're simply throwing money into the gas station's pump. When I switched from regular to midgrade I saw an immediate 3-4 MPG gain.


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## rbtec (Feb 3, 2012)

obermd said:


> As soon as your engine starts to knock, you lose fuel economy. Increasing the octane when you engine is knocking will improve your fuel economy. Increasing it when your engine isn't knocking won't. The question in the former is are you paying less per mile by increasing the octane to eliminate knocking. In the later case you're simply throwing money into the gas station's pump. When I switched from regular to midgrade I saw an immediate 3-4 MPG gain.


I have been think about going to 89 on my next fill up. Wish I could find E0 gas.


Sent from my Autoguide iPhone app


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## ErikBEggs (Aug 20, 2011)

obermd said:


> As soon as your engine starts to knock, you lose fuel economy. Increasing the octane when you engine is knocking will improve your fuel economy. Increasing it when your engine isn't knocking won't. The question in the former is are you paying less per mile by increasing the octane to eliminate knocking. In the later case you're simply throwing money into the gas station's pump. When I switched from regular to midgrade I saw an immediate 3-4 MPG gain.


The 1.4T does NOT knock at 87 octane. The cases documented on these forums were "bad gas" not a widespread thing. The engine will safely run on 87 octane because it is designed to. In extreme heat it may pull timing to avoid knock, but it will not knock. That is standard ECU compensation. If it did knock, me and the 200,000 other owners would have probably heard it at least once on 87 octane -_-. I only run 91 because I am tuned.

Even Vince in his Intelligent-Boost trifecta testing recorded no knock on 87 octane with even higher engine output (dynoed at 140HP / 190TQ on 87)


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## obermd (Mar 3, 2012)

ErikBEggs said:


> The 1.4T does NOT knock at 87 octane. The cases documented on these forums were "bad gas" not a widespread thing. The engine will safely run on 87 octane because it is designed to. In extreme heat it may pull timing to avoid knock, but it will not knock. That is standard ECU compensation. If it did knock, me and the 200,000 other owners would have probably heard it at least once on 87 octane -_-. I only run 91 because I am tuned.
> 
> Even Vince in his Intelligent-Boost trifecta testing recorded no knock on 87 octane with even higher engine output (dynoed at 140HP / 190TQ on 87)


I wonder how much knocking is eliminated by retarding the timing. If you go to 89 octane for a full tank and get better MPG on your normal driving, the ECU was retarding the firing timing. The only way to test this is to try. A single tank is sufficient to see the difference in mpg. If 89 improves your mpg, then you need to see if it reduced your fuel cost per mile. If it doesn't reduce your fuel cost, by all means stick with the 87. If 89 improves your mpg, I would run two or three tanks of 89 and then try a full tank of 91. Once again, if the mpg improves sufficiently to reduce your cost per mile for gas, stick with the 91. Otherwise drop back to 89.

The fact that a lot of us have discovered it's cheaper to run the next higher octane means the ECU is definitely retarding spark timing to counteract knock. The only question is whether your specific driving experience will improve with higher octane.


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## XtremeRevolution (Jan 19, 2012)

ErikBEggs said:


> The 1.4T does NOT knock at 87 octane. The cases documented on these forums were "bad gas" not a widespread thing. The engine will safely run on 87 octane because it is designed to. In extreme heat it may pull timing to avoid knock, but it will not knock. That is standard ECU compensation. If it did knock, me and the 200,000 other owners would have probably heard it at least once on 87 octane -_-. I only run 91 because I am tuned.
> 
> Even Vince in his Intelligent-Boost trifecta testing recorded no knock on 87 octane with even higher engine output (dynoed at 140HP / 190TQ on 87)


The fact that additional smoothness and performance is gained by going to 89 or 93 octane on the stock motor would indicate that the ECM retards timing for a reason. Other reviews have blatantly noted significant hesitation in hotter weather with 87 octane. What more proof do you need?

The fact that these cars are registering any degree of KR should indicate that you would get better fuel economy and performance with a higher octane fuel. Do we need to actually hear or feel the knock? If you get KR and signfiicant hesitation and loss of power on 87 octane and don't get that same KR and hesitation on 89 or 93 octane, the answer is pretty clear. 



obermd said:


> I wonder how much knocking is eliminated by retarding the timing. If you go to 89 octane for a full tank and get better MPG on your normal driving, the ECU was retarding the firing timing. The only way to test this is to try. A single tank is sufficient to see the difference in mpg. If 89 improves your mpg, then you need to see if it reduced your fuel cost per mile. If it doesn't reduce your fuel cost, by all means stick with the 87. If 89 improves your mpg, I would run two or three tanks of 89 and then try a full tank of 91. Once again, if the mpg improves sufficiently to reduce your cost per mile for gas, stick with the 91. Otherwise drop back to 89.
> 
> The fact that a lot of us have discovered it's cheaper to run the next higher octane means the ECU is definitely retarding spark timing to counteract knock. The only question is whether your specific driving experience will improve with higher octane.


^ This.


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## ErikBEggs (Aug 20, 2011)

I ran my first 4 tanks at 87 and tried 2 at 91 after... no change in MPG, slight improvement in acceleration smoothness at higher speeds (highway passing). My best tank was achieved using 87 Octane before I was even tuned or fully broken in. The engine is designed to run on 87 and in 95% of situations is perfectly fine doing so. It just leaves room for timing advance with the higher octane. I'm pretty sure someone datalogged that the 1.4T wasn't even retarding timing at 87 at all. With that being said, the cost per mile is less with 87, which is what I would run but I ordered the trifecta tune to help with the poor shifting. I've been running 91 Octane because of the tune, which is a vast improvement over stock.

It's obviously up to the user what fuel grade to run, but there is no point in telling everyone that premium fuel is required or recommended for this engine, because it's not.


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## XtremeRevolution (Jan 19, 2012)

ErikBEggs said:


> I ran my first 4 tanks at 87 and tried 2 at 91 after... no change in MPG, slight improvement in acceleration smoothness at higher speeds (highway passing). My best tank was achieved using 87 Octane before I was even tuned or fully broken in. The engine is designed to run on 87 and in 95% of situations is perfectly fine doing so. It just leaves room for timing advance with the higher octane. I'm pretty sure someone datalogged that the 1.4T wasn't even retarding timing at 87 at all. With that being said, the cost per mile is less with 87, which is what I would run but I ordered the trifecta tune to help with the poor shifting. I've been running 91 Octane because of the tune, which is a vast improvement over stock.
> 
> It's obviously up to the user what fuel grade to run, but there is no point in telling everyone that premium fuel is required or recommended for this engine, because it's not.


I recall hearing some tuner that did datalog and did record KR on 87 octane. It may not make a difference in colder weather, but the moment the weather warms up, the hesitation starts. When did you buy your Cruze, and in what weather conditions did you do all of these tests? If you did it in colder months (60 degrees or less), I wouldn't expect you to see a difference, but if you had tried it in the summer months in 85+ degree temperatures with A/C on, the story would have been different. 

Obviously, I have no proof past this article:
2011 Chevrolet Cruze LTZ: The Ultimate Hot Weather MPG Test - Regular vs. Premium



> Instead, the hot weather led to a very noticeable lack of drive-away power and sub-par highway fuel economy. Subsequent discussions with GM powertrain bigwigs and our own Jay Kavanagh revealed that small turbo engines are especially octane sensitive, which means their computers may agressively dial back the engine calibration in order to ward off knock in high load situations or in very hot weather.


Not much in the way of "proof." That said, we've had a bit of a cold spell in the US for the past month or so, but mark my words, when the weather warms up later this spring and this summer, there will be an influx of threads talking about hesitation, poor fuel economy, and loss of power, and I'll be there to tell them what I've said here.


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## obermd (Mar 3, 2012)

XtremeRevolution said:


> I recall hearing some tuner that did datalog and did record KR on 87 octane. It may not make a difference in colder weather, but the moment the weather warms up, the hesitation starts. When did you buy your Cruze, and in what weather conditions did you do all of these tests? If you did it in colder months (60 degrees or less), I wouldn't expect you to see a difference, but if you had tried it in the summer months in 85+ degree temperatures with A/C on, the story would have been different.
> 
> Obviously, I have no proof past this article:
> 2011 Chevrolet Cruze LTZ: The Ultimate Hot Weather MPG Test - Regular vs. Premium
> ...


This article shows the dramatic difference even an couple of mpgs can make. I noticed that on the premium the total miles was higher but the total fuel was lower. Like I said earlier and the article says, give it a try, you may be pleasantly surprised. The comments to the article also show that a number of different cars and not just turbo-charged cars benefit from higher octane.


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## shawn672 (Oct 31, 2010)

ErikBEggs said:


> The 1.4T does NOT knock at 87 octane.
> Even Vince in his Intelligent-Boost trifecta testing recorded no knock on 87 octane with even higher engine output (dynoed at 140HP / 190TQ on 87)



Vince was the one who originally told me 87 caused knock on the stock tune. He might have done something to get rid of that though with his tune.


edit: there was also the 3rd party article that saw 87 causing knock on stock tune under "heavy" heat


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## Higgs Boson (Mar 7, 2012)

obermd said:


> I'm not saying your speedometer is misreading. What I'm saying is that both Road & Track and Car & Driver have run Cruzes (LTZ and ECO) at over 120 MPH. If your Cruze is topping out in the 80s, is has a major problem.


So what you're REALLY saying is that's twice you have failed to have a sense of humor? Thanks for the serious responses, lol.


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## Beaker (Mar 21, 2012)

Why the heck are y'all still arguing over this. Buy what makes you happy.


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## Patman (May 7, 2011)

Where do you buy 91 octane fuel? Shell carries 87 89 and 93 same with BP and Speedway in Cincinnati. According to a google search, Sunoco carries 91. i think maybe back in the 80s they did along with 94 octaine. Now in Cinti they are 87 89 and 93 like everyone else. 




CruzeChick said:


> So after reading this discussion, I should put 91 in my cruze when I pick it up???


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## obermd (Mar 3, 2012)

Patman said:


> Where do you buy 91 octane fuel? Shell carries 87 89 and 93 same with BP and Speedway in Cincinnati. According to a google search, Sunoco carries 91. i think maybe back in the 80s they did along with 94 octaine. Now in Cinti they are 87 89 and 93 like everyone else.


In Denver, the octanes I have found (after starting to search for 91) are 85, 87, 89, and 91. The top octane rating is likely to vary from location to location and is most likely based on altitude. My Cruze is the first car I've driven that hates the 85 octane and doesn't particularly like 87 either. I've run Shell 91 for the past two tanks and have just shy of 700 miles on my current tank. I'll take pictures when I fill up on the way home and describe how I got 700+ miles on this tank when I get home.


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## obermd (Mar 3, 2012)

Higgs Boson said:


> So what you're REALLY saying is that's twice you have failed to have a sense of humor? Thanks for the serious responses, lol.


Higgs,

When it comes to personal transportation I don't have much of a sense of humor. If you notice my Sig you'll see two cars with "short" ownership with no obvious reason for the trade. I didn't trust the Fiero 2M4's engine and I didn't trust the clutch on the Lancer. A couple of months after I traded the Fiero 2M4 the first media reports of engine fires first appeared. I traded that car because the engine didn't sound right to me. The Lancer would for no reason simply not feel right when accelerating. In addition, the clutch would slip in 5th gear when the temperature was below freezing and running on cruise control. My feet weren't touching any pedals. Mitsubishi refused to even look for a problem, claiming that it was me riding the clutch pedal. I grew up in manuals and keep my foot of the clutch and hand off the shifter when I'm not actively shifting. I would have traded the Lancer for a 2011 ECO MT except I couldn't find one that I liked. After reading about all the problems with the 2011 Cruzen, I'm actually glad I kept the Lancer an additional year.

Don't even get my started about my wife's Dodge Intrepid - I wanted to paint it Lemon yellow and put text "Dodge Lemon" on each side.

I am glad you were trying to be humorous about your car and that you didn't actually have a problem.


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## XtremeRevolution (Jan 19, 2012)

I never saw 93 octane while I lived in LA. It was 87, 89, and 91. 



Beaker said:


> Why the heck are y'all still arguing over this. Buy what makes you happy.


This quote assumes that the sole purpose of this thread is to convince each other of what to buy or to tell someone else they've made poor buying decisions. 

Take a wild guess as to how many people visit this site on a daily basis who are not registered members. Take a guess as to how many will visit this specific thread over the next 12 months. At the end of the day, people are indeed free to make their own purchasing decisions and nobody can tell them what to do with their money, but one must also respect the fact that complete and accurate information must at some point be given for the sake of those who are now and will in the future be seeking that information regardless of whether or not they post or register on this forum.


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## Beaker (Mar 21, 2012)

Yes but y'al have been going back and forth on it in several threads. Neither of you will relent. So I think the guest readers can either read, see both arguments, and decide for themselves with the information at hand, or remain blissfully ignorant to whatever they were already doing.


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## sedanman (Dec 10, 2010)

My Cruze runs slow on 87 octane, great on Shell's 89 octane and good on 93 octane (diminishing returns, due to stock tune I guess). Computer is definitely retarding timing on 87. Sure 87 is perfectly safe, but it's not optimal.

Each person can try them all and make their own decision.


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## ErikBEggs (Aug 20, 2011)

shawn672 said:


> Vince was the one who originally told me 87 caused knock on the stock tune. He might have done something to get rid of that though with his tune.
> 
> 
> edit: there was also the 3rd party article that saw 87 causing knock on stock tune under "heavy" heat


Hmmmm, Vince does have our tune running a lower coolant temp than stock as well, probably a difference there. He recorded no knock on the 87 Intelliboost tune in the initial tests


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## ErikBEggs (Aug 20, 2011)

shawn672 said:


> Vince was the one who originally told me 87 caused knock on the stock tune. He might have done something to get rid of that though with his tune.
> 
> 
> edit: there was also the 3rd party article that saw 87 causing knock on stock tune under "heavy" heat


Hmmmm, Vince does have our tune running a lower coolant temp than stock as well, probably a difference there. He recorded no knock on the 87 Intelliboost tune in the initial tests. But weather probably plays a factor since it was cool temps.



Patman said:


> Where do you buy 91 octane fuel? Shell carries 87 89 and 93 same with BP and Speedway in Cincinnati. According to a google search, Sunoco carries 91. i think maybe back in the 80s they did along with 94 octaine. Now in Cinti they are 87 89 and 93 like everyone else.


91 Octane fuel is usually used out west. It is also available at select stations in the NE. NOCO is in NY state and sells 91, and Sunoco sells four grades at most stations - 87, 89, 91, 93. The 91 is labeled "premium" (93 is Ultra 93) is anywhere from $.02 to $.15 / gal less expensive than 93 and works for nearly every car that requires "Premium" fuel since the cutoff is 91. If you don't have access to 91 Octane and your car calls for 91, some people just use half 93 and half 89. It can save you a good $1-2 / fill up since that is about halfway between the grades.


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## Higgs Boson (Mar 7, 2012)

obermd said:


> Higgs,
> 
> When it comes to personal transportation I don't have much of a sense of humor. If you notice my Sig you'll see two cars with "short" ownership with no obvious reason for the trade. I didn't trust the Fiero 2M4's engine and I didn't trust the clutch on the Lancer. A couple of months after I traded the Fiero 2M4 the first media reports of engine fires first appeared. I traded that car because the engine didn't sound right to me. The Lancer would for no reason simply not feel right when accelerating. In addition, the clutch would slip in 5th gear when the temperature was below freezing and running on cruise control. My feet weren't touching any pedals. Mitsubishi refused to even look for a problem, claiming that it was me riding the clutch pedal. I grew up in manuals and keep my foot of the clutch and hand off the shifter when I'm not actively shifting. I would have traded the Lancer for a 2011 ECO MT except I couldn't find one that I liked. After reading about all the problems with the 2011 Cruzen, I'm actually glad I kept the Lancer an additional year.
> 
> ...


Well, there really aren't many truly 100% reliable makes out there, anything Mopar (Dodge, Jeep, Chrysler, etc) are all crap, Mitsu is crap, Nissan is mediocre, Honda and Toyota have good reputation but have their share of issues.....Lexus is pretty good, Porsche is the only European make I would dare own, Chevy and Ford is going to be hit or miss.....

The real trick is not building an expectation about your vehicles (or anything in life). They WILL break. Such is life. It's too short to develop your identity around it. So many other things to enjoy rather than spend your time remembering the bad.....I mean, you can learn from mistakes but you can't predict the future either..... You have to take your hits in life and keep going, no matter how protected you think you are or how wise you think you have become, you're still going to get hit, screwed, taken advantage of, etc. Don't let it get you down, it's life and as long as you live, life will happen.


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## obermd (Mar 3, 2012)

Higgs Boson said:


> Well, there really aren't many truly 100% reliable makes out there, anything Mopar (Dodge, Jeep, Chrysler, etc) are all crap, Mitsu is crap, Nissan is mediocre, Honda and Toyota have good reputation but have their share of issues.....Lexus is pretty good, Porsche is the only European make I would dare own, Chevy and Ford is going to be hit or miss.....
> 
> The real trick is not building an expectation about your vehicles (or anything in life). They WILL break. Such is life. It's too short to develop your identity around it. So many other things to enjoy rather than spend your time remembering the bad.....I mean, you can learn from mistakes but you can't predict the future either..... You have to take your hits in life and keep going, no matter how protected you think you are or how wise you think you have become, you're still going to get hit, screwed, taken advantage of, etc. Don't let it get you down, it's life and as long as you live, life will happen.


I do have an expectation that the vehicle will at least last through the warranty period without too many problems. I do believe that unless you learn from the bad you can't improve. I agree with taking hits and continuing. However, I won't knowingly put myself in the same position to take the same hit again if I can avoid it, thus Dodge and Mitsubishi are both on my no-buy list for a long time. If my second Fiero hadn't been so good I would probably not have purchased the Transport. As it was I was very concerned about what I would buy after Pontiac was shut down. I think I found the answer in Chevy, but only time will tell. I know both Pontiac and Chevy are divisions of GM, but at the time Pontiac was killed Chevy didn't have anything I was interested in.


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## obermd (Mar 3, 2012)

Back to the topic of this thread, I have determined via filling that tank and driving the car that 89 octane is sufficient for my ECO MT until the temps go above 80. We have had several days in Denver this year above 80. Above 80 I need to run 91 octane to avoid acceleration issues. Thus my recommendation to anyone driving the 1.4T engine is to try different octane grades and see what happens. 87 may not be the best for your situation. On the other hand 87 may be the best. There are too many driving situations and styles to definitely state that the stock 1.4T tune requires a specific grade of gas.


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## 70AARCUDA (Nov 14, 2010)

Here is an excerpt from page 60 (of 81) of GM's document to EPA, "2013 Model Year Compliance Statements," worth reading (draw your own conclusions):

_"*2013 MODEL YEAR*
*COMPLIANCE STATEMENTS*
*91 RON FUEL TESTING COMPLIANCE
*
The knock sensor does not activate in any way during the FTP (or the SFTP as applicable) and the HWFET, and the calibration is designed to operate on 91 RON gasoline without the need for spark adjustment.

The city and highway fuel economy test result differences between comparing 91 RON operation and 96 RON operation is within 3%, and there are no emissions increases (beyond normal test variability) using 91 RON fuel when tested on the FTP (or SFTP, as applicable)."
_
Source: GM document to EPA, 86.1844(d)(8)-DGMXV01.8031:

http://iaspub.epa.gov/otaqpub/display_file.jsp?docid=29142&flag=1


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## smitty (Nov 21, 2013)

*Cold Weather?*

I know that the 1.4 is very picky on Octane in the summer - I know firsthand, but what about when it is cold? Say Upstate NY winter cold? Should I still run 91 like I usually do or will lower Octanes be fine (for power and responsiveness)? I do not know yet because I just bought my 2014 Cruze this summer. Thanks.


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