# I don't understand why you're using 87!



## titan2782 (Nov 4, 2011)

This is in response to a ton of previous posts about the trifecta tune and 87 octane and also to the recently announced budget tune.

I never understood why you would want to spend the money to get extra performance but you won't spend the money on the proper octane fuel to make sure you get that performance. Let's do some math.

I Fill up at Chevron stations exclusively (most expensive, but better quality). Last time I fueled up the prices were:

91: $4.89/gal x 10 gal = $48.90
89: $4.79/gal x 10 gal = $47.90
87: $4.69/gal x 10 = $46.90

Assuming you drive 20,000 miles a year and you get 35mpg = ~571 gallons

Yearly totals: (PPG * 571)
91: ~$2792
89: ~$2735
87: ~$2677

The savings from using 87 over 91 is ~$115/year. 

You likely spend more than this at Mc Donalds over a 3 month period. I ran the cheapest 87 in my Kia because I didn't care about it. 1) I care about my Cruze. 2) I would never run 87 with a forced induction setup, even with as small of a motor as we have. I realize the user manual says it's fine to run 87, but why do you insist on running 87?

Am I missing something or is my math off?


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## NeonRyder (Jan 3, 2012)

GM sent an update to run 91 octane in hot temps etc. I end up running 93 because I can never find 91. I also had detonation/hesitation before switching octanes...


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## AkotaHsky (Feb 11, 2012)

I only run premium since the day I bought it.


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## kfr291 (Aug 11, 2012)

is that just for tunes? or is that for all thier cars? i do not have a tune on mine and i run 89 normally


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## jblackburn (Apr 14, 2012)

Holy crap on a stick, where are you paying $4.89 for gas?!


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## titan2782 (Nov 4, 2011)

SoCal (out skirts of LA area). Will be over $5/gal in a few days. We have a refinery shut down. Also, if I went to Arco it would be probably $4.69 for 91 but that's low quality gas. We'll be going to the winter blend at the end of the month and then the prices will drop to around $4.00

We don't have 93 out here, only 91.


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## obermd (Mar 3, 2012)

NeonRyder said:


> GM sent an update to run 91 octane in hot temps etc. I end up running 93 because I can never find 91. I also had detonation/hesitation before switching octanes...


Can you get us a reference to this update?


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## obermd (Mar 3, 2012)

A lot of us run 91/93 in the summer. I am currently experimenting with 87 (89 at sea level) for the cooler months. See my thread http://www.cruzetalk.com/forum/27-fuel-economy/9130-cooler-weather-lower-octane-ls-eco.html for how this is going.

You are missing one thing in your calculations - many of us see better fuel economy with higher octane. It becomes what is the best bang (MPG) for the buck.


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## silverls (Nov 12, 2011)

This is the year 2012. The car is made to run on 87 and so i run 87. Simple as that. My car is stock. But if i bought a tune that was fine on 87, i would still run it. Why spend the extra money if I dont have to is my ideology. 

I can understand your point. But if 87 was so horrible i would have had cars destroyed a long time ago. I do care about my car. But this forced induction system was made to run fine on 87. So there is no problem with it. 

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## iKermit (Dec 13, 2010)

I have only but twice in my whole ownership of my Cruze have put 87 in it and it wasn't by choice... I did feel a HUGE difference in MPG and performance... and i don't even have the 1.4.

And plus your math is correct...


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## titan2782 (Nov 4, 2011)

silverls said:


> This is the year 2012. The car is made to run on 87 and so i run 87. Simple as that. My car is stock. But if i bought a tune that was fine on 87, i would still run it. Why spend the extra money if I dont have to is my ideology.


The difference in cost is insignificant compared to the potential benefits. Do you buy the cheapest oil & filter you can find for your oil changes too? Money is wasted when you limit the car's potential after dropping untold dollars into parts. 



> I can understand your point. But if 87 was so horrible i would have had cars destroyed a long time ago. I do care about my car. But this forced induction system was made to run fine on 87. So there is no problem with it.


The cars might "run ok" with 87 but they won't be optimal. The cars are designed to protect themselves and if that comes at the cost of MPG & performance, so be it.

Being stock I can understand where you're coming from. My point was about the people who want high performance but only if they can run 87. Whats the point in that?

Maybe I'm too anal about it. Heck, I only use a specific Chevron station and I always use the same pump.

But I'm also just as anal about the reverse. I don't understand what owners of stock n/a hondas think they'll get by using 91 instead of 87.


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## titan2782 (Nov 4, 2011)

iKermit said:


> I have only but twice in my whole ownership of my Cruze have put 87 in it and it wasn't by choice... I did feel a HUGE difference in MPG and performance... and i don't even have the 1.4.
> 
> And plus your math is correct...


My wife put in 89 by mistake a week after we got the car. It ran noticeably different. Performance was degraded.


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## XtremeRevolution (Jan 19, 2012)

silverls said:


> This is the year 2012. The car is made to run on 87 and so i run 87. Simple as that. My car is stock. But if i bought a tune that was fine on 87, i would still run it. Why spend the extra money if I dont have to is my ideology.
> 
> I can understand your point. But if 87 was so horrible i would have had cars destroyed a long time ago. I do care about my car. But this forced induction system was made to run fine on 87. So there is no problem with it.
> 
> Sent from my DROID BIONIC using AutoGuide.Com Free App


Send me your paypal address, and I will *give *you $3 to make up for the difference in running 93 octane over 87 octane, just so you would see for yourself why the vast majority of stock Cruze owners who have run a higher octane fuel will never go back to 87 octane.


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## NYCruze2012 (Jan 16, 2012)

XtremeRevolution said:


> Send me your paypal address, and I will *give *you $3 to make up for the difference in running 93 octane over 87 octane, just so you would see for yourself why the vast majority of stock Cruze owners who have run a higher octane fuel will never go back to 87 octane.


Amen to that! I use to run 87 in my Eco 6 speed and it was a dog. I will never go back. I'll tell you for the couple bucks extra is totally worth it to run 93.

Sent from my DROID3


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## silverls (Nov 12, 2011)

titan2782 said:


> The difference in cost is insignificant compared to the potential benefits. Do you buy the cheapest oil & filter you can find for your oil changes too? Money is wasted when you limit the car's potential after dropping untold dollars into parts.
> 
> 
> 
> ...


I get my oil changes done at the dealership with factory oil and filter every 4000 miles or 4 months. But that is only because it is a new car. In the past I have put 200,000 miles on 2 consecutive vehicles using advance auto parts brand oil and yes, the cheapest filter they had. Every 4,000 miles or 4 months. Any neither car had any engine trouble and were still good running vehicles when i sold them with over 300k total miles. So you can understand why I do not play into oil hype. 

1. I did not buy this car for performance. I bought it to drive like a grandma and get good gas mileage. I don't consider my. Car to run "ok" i have absolutely no detonation/blowout/hesitation. Even under load when i do step on it. It runs and drives as i would expect it to. So i consider it to run perfectly. 

In regards to mpg, the mpg jump when using high octanes does not justify the cost in my opinion. In my own recording i made the same trip with 87 and 93. Climate remaining very close to the same (trips made within 2 days of each other) I recorded a 1.4mpg jump on 100% highway driving. For my daily commute the margin was even less.
To me there is no point in paying the extra $. Even on my daily commute which is 85% city i average close to 40mpg running 87 octane. You will have to take my word for it at this point because ny fuelly account is messed up.



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## Beachernaut (Mar 27, 2012)

Meh... Run what you're comfortable with. 

That said, I do notice some difference between 87 and 91 (no 93 here) and don't mind the bit extra to run premium.


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## sciphi (Aug 26, 2011)

I'm tuned, so I run 93 octane. I don't get the option for 91 around here. It's either 89 or 93. :signlol:

Paraphrasing the most awesomest guy in the whole wide world (at least according to the commercials), "I don't always drive at wide open throttle. But when I do, I prefer 93 octane." 

Reason being, these engines are likely responding reactively to knock. Yeah, some will be compensated for automatically by the low-octane tables when running 87 octane. I'd still prefer to give the engine as much protection against knock as possible, just in case the worst-case scenario of peak boost, too much timing, and too little fuel happens. I don't feel like chipping a piston or worse. 93 octane over a year is far cheaper than a used 1.4T longblock.


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## obermd (Mar 3, 2012)

titan2782 said:


> This is in response to a ton of previous posts about the trifecta tune and 87 octane and also to the recently announced budget tune.
> 
> I never understood why you would want to spend the money to get extra performance but you won't spend the money on the proper octane fuel to make sure you get that performance. Let's do some math.
> 
> ...


I have measured improved MPG when I run on 91 vs 87 octane (sea level) of about 3 MPG. Given your numbers, 91 octane will cost me $2573 to drive 20,000 miles, which is $104 less than your price at 87 octane. Even a 2 MPG improvement will make the 91 octane cheaper per mile and will definitely make the car run smoother.


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## 70AARCUDA (Nov 14, 2010)

NeonRyder said:


> GM sent an *update* to run 91 octane in hot temps etc. I end up running 93 because I can never find 91. I also had detonation/hesitation before switching octanes...


Did GM send that *update* directly to you or did you get it through your dealership Service Department? Either way, is there an identifying number on that *update *so that others might request a copy from GM?


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## leeclark (Mar 25, 2012)

only time mine got a full tank of 87 was the day i drove it off the lot cause the dealer. after that tank was gone it has not had anything other than 93 in it. and i try to find e0 gas but only if its on my way.


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## coinneach (Apr 10, 2012)

I used 87 initially because that's what's called out in the manual. I used it post-tune as well because I figured it wouldn't make much difference on the 1.8. I was wrong; she bogged and hesitated badly. Six months on, I've found Penny's sweet spot - no tune, plugs .034", 89 octane. Took some experimenting and tweaking to get her to this point, but that's OK.


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## OnlyTaurus (Mar 20, 2012)

I never understood the 'OK' for 87 either.. I ran the 87 I got from delivery, then ran TopTier 93 ever since. I'll never go back.

I was surprised when 87 was considered ok, I thought the turbo engines would be premium only, and I was preparred to pay it.

Even on the stock ~12lbs of boost, WOT is creating quite the compression ratio. The stock computer must really be retarding the timing under WOT, there's no way it could be 2-4 degrees ATDC with that kind of heat the compression is creating. Definitely a recipe for knock(not to mention disaster).

I'm tuned, and I don't know how much Vince had to adjust on our ECMs to get proper timing for piston thrust, but I'd imagine he really had to toy with the tune before marketing it.


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## Hoon (Mar 18, 2012)

This is one of those never ending debates that's blown out of proportion and over-thought.

Bottom line, it's 2012. That means 2 things...1) You cannot succeed in the market with an economy car that takes anything besides 87 octane, and 2) PCMs have evolved to the point that they can react to knock quickly and effectively enough to keep internals safe on lower octane fuel, within reason. Tons of cars these days regularly knock on their recommended fuel in stock trim. European cars, Japanese cars, American cars, makes no difference, everything now is factory tuned near the knock threshold. 

Now, i don't have the ability to log my cruze yet, but from the butt dyno my Cruze PCM reacts much more quickly and more drastically during knock situations than my old Mitsubishi ECM ever could. I tuned that car typically around 30psi on straight 93 (no meth). In knock situations if i left my foot down (street racing usually) the ECM would pull a couple degrees of timing. The reduction in power was barely noticeable. On one occasion this led to a blown head gasket during a 4th gear pull up a steep hill on a bridge (a situation of abnormally high load). 

In contrast, when towing up long highway hills with the Cruze, i will get a series of very quick, sharp reductions in power. It feels almost like a misfire and the power is back instantly...then the cycle repeats as the PCM fights to keep the motor making power with high IATs and the beginnings of knock. The technology is far better than it used to be. 

Another point, knock isn't a black and white thing, there are infinite shades of gray. At stock boost levels, brief flecks of mild knock aren't going to cause any immediate damage...hence why GM gives us 100K warranties and cars that begin to knock stock. When you increase the boost the margin of error gets a lot smaller, but even at tuned boost levels (which are still very low compared to the serious turbo world) the PCM can do a good job to regulate knock before it becomes an actual issue. 

Bottom line, anything more than 87 octane is basically peace of mind. I run 89 because it seems to make sense. I get the same MPG on 89 that i do on 93, and with the increase in mpg it costs the same to run 87 or 89. I use and abuse my car in ways that are more severe than intended, so i like the added security of slightly higher octane....but if I filled up with 85 octane, hitched up a loaded trailer and floored it up the steepest hill i could find in 6th gear, i'm sure the PCM would keep the rods in the motor. 

I've seen people make some pretty huge tuning mistakes on late model cars and get away with things that would scatter internals all over the highway 10 years ago. 

Now, if you're running a tune designed for 91+, use 91+. That tune is engineered to keep the car safe with that fuel in most situations...which means in that occasional situation where the tune is too hot, the computer has adequate time to react and prevent the knock. If you use 87, you've greatly reduced if not completely eliminated the margin of error. 



OnlyTaurus said:


> The stock computer must really be retarding the timing under WOT, there's no way it could be 2-4 degrees ATDC with that kind of heat the compression is creating.


It's definitely not anything ATDC. 

Timing in these cars is very low, high single digits BTDC. I think even on the stock map they can get down in the 8-9* BTDC range.


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## obermd (Mar 3, 2012)

My dealer put 85 in both my Cruzen. The Cruze is the only car I've owned/driven that said to run 87 that wouldn't run well on 85 here in Denver.


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## OnlyTaurus (Mar 20, 2012)

Well said Hoon. I'm actually curious about the timing. I may slap GDS on the Cruze and do some pulls, see what true values are.

I'll post when I get it.


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## audiobahnman (Sep 2, 2011)

hmm must be the extra compression.. I live in the Black Hills and my 1.8 cruze runs great on 85 octane as have all of my cars 

That said, I have ran 91octane also there is some performance increase just not enough to justify it at our prices. 

Premium here is about tied with diesel for price or about 40-50 cents higher than regular


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## The_Madcat (Oct 6, 2012)

If you run 87 octane and one day decide to use 91+ and notice the gas mileage is better... Then the engine does not run "fine" on 87. The PCM is sensing the damaging knock/ping the 87 octane is causing and retarding your timing to protect the engine. This causes not only performance loss, but because of the performance loss, you will lose mpg's as well. This is with any modern, computer controlled engine. If you increase the octane but notice no difference in mpg's or performance, the only thing you are doing is wasting money at the pump. I have seen enough threads on this subject here to recommend 91+. Anything over that seems to give no noticeable benefit.

My .02$.


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## titan2782 (Nov 4, 2011)

The_Madcat said:


> If you run 87 octane and one day decide to use 91+ and notice the gas mileage is better... Then the engine does not run "fine" on 87. The PCM is sensing the damaging knock/ping the 87 octane is causing and retarding your timing to protect the engine. This causes not only performance loss, but because of the performance loss, you will lose mpg's as well. This is with any modern, computer controlled engine. If you increase the octane but notice no difference in mpg's or performance, the only thing you are doing is wasting money at the pump. I have seen enough threads on this subject here to recommend 91+. Anything over that seems to give no noticeable benefit.
> 
> My .02$.



I would only argue the 91+ point for forced induction motors. The n/a 1.8 may not have any issues with 87 unless it has super high compression ratio, drives at 8000ft, drives in extreme heat or has some crazy timing. 

I heard the attendant at a chevron the other night tell a girl that she'll get better mileage, up to 5 mpgs, if she went with the premium fuel. I immediately called him out and told him not to spread that BS. You should be running the proper octane for your application which is why I don't understand using 87 on forced induction motors. 

For those running 87 in their 1.4T I at least hope you're using quality fuel. In SoCal, Velaro and Arco are the worst (but cheapest). I wouldn't even buy premium from them.


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## Hoon (Mar 18, 2012)

OnlyTaurus said:


> Well said Hoon. I'm actually curious about the timing. I may slap GDS on the Cruze and do some pulls, see what true values are.
> 
> I'll post when I get it.


Thanks man, let me know what the values look like. 



audiobahnman said:


> hmm must be the extra compression.. I live in the Black Hills and my 1.8 cruze runs great on 85 octane as have all of my cars


It's actually the turbo. At elevation where the air is thin an N/A motor draws in the same air volume, but because of the lower air density you get a lot less air mass, which has the effect of lowering compression. In a turbo motor, the effect is reduced because the turbo is forcing in an air mass closer to what you would get at sea level....meaning the octane demand is reduced in the N/A motor more than the boosted motor. 



The_Madcat said:


> If you run 87 octane and one day decide to use 91+ and notice the gas mileage is better... Then the engine does not run "fine" on 87. The PCM is sensing the damaging knock/ping the 87 octane is causing


I don't disagree that 87 causes knock, but there is no evidence whatsoever that it causes knock severe enough to result in any damage. 

According to the engineers that designed it and the accountants standing behind it, it does run fine. I personally run more octane because i'd like the added safety margin, but that doesn't mean the car wouldn't be completely "fine" on 87.

I agree that 87 isn't optimal, but there is no way you can argue that anything more than 87 is needed in the overwhelming majority of situations. 



titan2782 said:


> I would only argue the 91+ point for forced induction motors. The n/a 1.8 may not have any issues with 87 unless it has super high compression ratio, drives at 8000ft, drives in extreme heat or has some crazy timing.
> 
> I heard the attendant at a chevron the other night tell a girl that she'll get better mileage, up to 5 mpgs, if she went with the premium fuel. I immediately called him out and told him not to spread that BS. You should be running the proper octane for your application which is why I don't understand using 87 on forced induction motors.
> 
> For those running 87 in their 1.4T I at least hope you're using quality fuel. In SoCal, Velaro and Arco are the worst (but cheapest). I wouldn't even buy premium from them.


87 is the proper octane for the application. 

You're lumping all FI engines together like they're the same thing. 1 Liter in my last car made 265hp. 1 Liter in my cruze makes about 100hp. 87 would scatter my big turbo 4G63 motor in a few seconds at 30+psi, but 400k+ Cruzes have been driving many millions of miles on 87 and to my knowledge there hasn't been one engine failure attributable to detonation. 

As for the quality fuel thing, the difference is the additives. Octane is the measured resistance to knock, so anything labeled 93 will perform about the same. I could never draw any conclusive results regarding knock resistance when tuning my car at 30+psi experimenting with various brands of 93, so you're not going to see a difference in a cruze on 12-14psi.

Now carbon buildup over time might be affected, which might affect knock 10K miles down the road...but that's a long term side effect, not an immediate direct result.


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## obermd (Mar 3, 2012)

We've been down the octane road discussion before. The reality is that if you're happy with 87, use it. If you are like me and don't like having your throttle pulse like the car is misfiring, boost your octane until the throttle pulse is reduced to a level you're comfortable with. As your throttle pulsing is reduced you will see an increase in overall fuel economy and vehicle performance. The question then becomes "is the extra pump price for the higher octane offset by the reduction in fuel consumed?" Using OPs numbers in the first post of this thread, the increase seen from increasing octane more than covers the increased price/gallon.


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## Hatje (Jun 23, 2011)

Lol the debate never ends !

I run 87 not worth 91 or 94 octane in Canada is expensive If you want "performance" buy a sports car


Sent from my iPhone using AG Free


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## titan2782 (Nov 4, 2011)

Hatje said:


> Lol the debate never ends !
> 
> I run 87 not worth 91 or 94 octane in Canada is expensive If you want "performance" buy a sports car
> 
> Sent from my iPhone using AG Free


:uhh:

I think you're response should have included "TL;DR"


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## ErikBEggs (Aug 20, 2011)

Filled up today. Prices: 87: $4.09 / 89: $4.19 / 91: $4.27 / 93: $4.35 Gotta love New York. Super high across the board, but the fact that I can get Premium (91) for only $.18 / gal more than regular eases the pain. In Michigan last weekend I paid $4.34 for some 93 (no 91 offered!) when the price of regular was $3.78. Just pure ******* robbery.


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## audiobahnman (Sep 2, 2011)

Nice if it was only an 18cent spread from regular to premium here, I would be running premium all of the time.


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## titan2782 (Nov 4, 2011)

audiobahnman said:


> Nice if it was only an 18cent spread from regular to premium here, I would be running premium all of the time.


What is the spread? It's always +10 for 89 and +20 for 91 here in so cal. Remember, at 20 cents it's only an additional ~2.50 per 10 gallons (assuming my $4.89/gal figures). You can't spare $2.50?

Story:
When we were moving back from Kansas to California, we'd decided to go visit friends in Colorado on the way so instead of taking the 40 through New Mexico/Arizona, we went through the rockies. Needless to say once we started into Colorado, the moving truck would only get to about 30 mph and then it would start running really rough. It was jerking and cutting out and the engine light was flashing at us. We kept it under 30mph for a while but obviously that wasn't going to cut it. We pulled into a gas station to fill up. I was about ready to call the truck company and see if there was something they could do. That's when I noticed the pumps. Instead of the 87 we had been buying (or thought we were buying), we were in fact buying 85! Needless to say, I fueled up with 89 and added some octane booster and it was 80mph the rest of the way home. 

Moral: 
It ran "OK" as long as we didn't ask anything of it. But when we needed it to work properly (do what it was built and intended to do) it couldn't.


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## audiobahnman (Sep 2, 2011)

3.60 regular 4.00 Premium and 4.12 Diesel thats the current good deals here so 40cents at the moment


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## titan2782 (Nov 4, 2011)

audiobahnman said:


> 3.60 regular 4.00 Premium and 4.12 Diesel thats the current good deals here so 40cents at the moment


Where do you live? I haven't see a spread like that before. In your case, it's an additional $229/year or $20/mo. That seems a little more significant. But again I bet you spend that per month in the app store.


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## Big Tom (Mar 8, 2011)

After 40,000+ miles of tracking mileage, my car gets 4% better using 93 over 87.


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## audiobahnman (Sep 2, 2011)

20 bucks a month sounds about right .... 
I am in Rapid City, SD and those are Sams Club prices. Gasbuddy says they're the lowest..

thats 85 E0 and 91E0 gas at a 40cent spread .... (no ethanol for my baby)

I'll be honest I work at Menards full time and am not rich so thats alot to me.
I use a basic flip phone by the way, and try to live efficiently, thats why I bought the cruze. 

I do have the Trifecta tune but the motor is currently stock , just the trans is flashed at the moment.


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## audiobahnman (Sep 2, 2011)

Big Tom said:


> After 40,000+ miles of tracking mileage, my car gets 4% better using 93 over 87.


just saw your post at my prices thats 4.00/3.60 or an 11.1% increase in cost for a 4% increase in range .... thats why I put my motor tune to stock and am using regular for now.... until prices get better


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## titan2782 (Nov 4, 2011)

Food for thought:

As far as the "they have to run on 87 to compete in this market", look at the SMART car. It requires 91. That little 3cyl 1ltr has such a high compression ratio that it needs high octane fuel. High C/R is the only way it can make any power. I don't know about the sales statistics (tried looking), but my point is that they went into the market with their 40mpg car. The trend for bigger MPG #'s seems to be going with smaller motors but the problem with smaller motors is power. One solution to lacking power is forced induction. Great example is Ford and their ecoboost setup. "Through the use of direct injection, the engine needs only regular-grade gasoline to run, though premium fuel is recommended." I bet it recommends you use premium if you plan on using the truck as it was intended. The ecoboost has a tow capacity that matches trucks with 6.2L setups. I'd like to see you to 11,000 pounds up a grade while running 87. Better grab a snack, it's going to be a while. 

Forgot what my point was. It's late.


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## Big Tom (Mar 8, 2011)

And on the butt dyno, it feels like a 20% boost with the 93. When it's below 32 degrees I will use 87 most of the time, over 80 degrees it will be 93 100% of the time.


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## audiobahnman (Sep 2, 2011)

its cool man ... ive owned cars that had blowers in the past... so I understand, i'm just slow now with my 1.8L NA i'm getting older


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## Big Tom (Mar 8, 2011)

We have E10 here, you are lucky to have E0.


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## Hoon (Mar 18, 2012)

titan2782 said:


> Story:
> When we were moving back from Kansas to California, we'd decided to go visit friends in Colorado on the way so instead of taking the 40 through New Mexico/Arizona, we went through the rockies. Needless to say once we started into Colorado, the moving truck would only get to about 30 mph and then it would start running really rough. It was jerking and cutting out and the engine light was flashing at us. We kept it under 30mph for a while but obviously that wasn't going to cut it. We pulled into a gas station to fill up. I was about ready to call the truck company and see if there was something they could do. That's when I noticed the pumps. Instead of the 87 we had been buying (or thought we were buying), we were in fact buying 85! Needless to say, I fueled up with 89 and added some octane booster and it was 80mph the rest of the way home.
> 
> Moral:
> It ran "OK" as long as we didn't ask anything of it. But when we needed it to work properly (do what it was built and intended to do) it couldn't.


That happens with older vehicles....especially carb'd trucks. About what year was the van/truck?



titan2782 said:


> Food for thought:
> 
> As far as the "they have to run on 87 to compete in this market", look at the SMART car. It requires 91. That little 3cyl 1ltr has such a high compression ratio that it needs high octane fuel. High C/R is the only way it can make any power. I don't know about the sales statistics (tried looking), but my point is that they went into the market with their 40mpg car. The trend for bigger MPG #'s seems to be going with smaller motors but the problem with smaller motors is power. One solution to lacking power is forced induction. Great example is Ford and their ecoboost setup. "Through the use of direct injection, the engine needs only regular-grade gasoline to run, though premium fuel is recommended." I bet it recommends you use premium if you plan on using the truck as it was intended. The ecoboost has a tow capacity that matches trucks with 6.2L setups. I'd like to see you to 11,000 pounds up a grade while running 87. Better grab a snack, it's going to be a while.
> 
> Forgot what my point was. It's late.


The Smart is actually anything but smart. It's been a complete failure in the market. When they first came out they were selling 2K cars a month, which plummeted in one year. In 2010 they were down to a few hundred cars a month...compared with 20K+ Cruzen. 

Also, the compression ratio is low, only 10:1. I really have no idea why that POS engine needs 91+. None. It has no compression, makes no power (70 hp lol), and isn't efficient...yet requires premium fuel....very Smart engineering. 

As for the Eco-boost, DI goes a long way. I'm sure it runs well on 87...nothing like that old moving truck. 



Big Tom said:


> And on the butt dyno, it feels like a 20% boost with the 93.


lol



Big Tom said:


> We have E10 here, you are lucky to have E0.


I want E85 dammit.


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## BeeoBeeo (Sep 23, 2012)

Running a bit of an experiment with my Holden Cruze SRi at the moment, on RON91 im getting about 600Km from a tank.

For RON98 to be cost effective i need to get an extra 58Km from the tank.

When i fill up with RON91 i get an estimated 600Km from the trip computer, when i filled up with RON98 i got an estimated 644Km on the trip computer, since then i have done 180Km and the estimated range has dropped to 587Km so looking good so far.

I've noticed the throttle response is a bit sharper and the engine is running a lot nicer.

Will let you guys know the results .


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## jblackburn (Apr 14, 2012)

titan2782 said:


> What is the spread? It's always +10 for 89 and +20 for 91 here in so cal. Remember, at 20 cents it's only an additional ~2.50 per 10 gallons (assuming my $4.89/gal figures). You can't spare $2.50?
> 
> Story:
> When we were moving back from Kansas to California, we'd decided to go visit friends in Colorado on the way so instead of taking the 40 through New Mexico/Arizona, we went through the rockies. Needless to say once we started into Colorado, the moving truck would only get to about 30 mph and then it would start running really rough. It was jerking and cutting out and the engine light was flashing at us. We kept it under 30mph for a while but obviously that wasn't going to cut it. We pulled into a gas station to fill up. I was about ready to call the truck company and see if there was something they could do. That's when I noticed the pumps. Instead of the 87 we had been buying (or thought we were buying), we were in fact buying 85! Needless to say, I fueled up with 89 and added some octane booster and it was 80mph the rest of the way home.
> ...


40 cents a gallon spread here. Jerks.


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## Patman (May 7, 2011)

jblackburn said:


> 40 cents a gallon spread here. Jerks.



Cincinnati also does the 10 cent spread at most stations except for corporate Shell stations then it is 87 + 10 for 89 + 14 for 93 and shell has a deal with Kroger to 10 off cents if you spend $100 + at Kroger which is not hard to do for groceries in a week(esp since gas prices are so high) and shipping raises cost. For the most part I have been @ $4.00 a gal for 93 premium at shell with the 10 cents off. Now that I have a CAI, that is why I have been considering removing my tune to run 89 $40 a fill up is getting hard to swallow since I have not had a raise in 6 years and everything else is going up in price also(gas + electric and water).


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## silverls (Nov 12, 2011)

Because i have to restart my fuelly account anyway. (Long story) i am gonna do a few test tanks. I have to go fill ip today so i am gonna fill up with 89 instead of ny normal 87. And next tank i will move up again. Obviously i will have to runn a few tank if each to get an average. So this is gonna take me a while seeing as a tank lasts me almost 3 weeks. 

Sent from my DROID BIONIC using AutoGuide.Com Free App


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## sedanman (Dec 10, 2010)

OnlyTaurus said:


> I never understood the 'OK' for 87 either.. I ran the 87 I got from delivery, then ran TopTier 93 ever since. I'll never go back.
> 
> I was surprised when 87 was considered ok, I thought the turbo engines would be premium only, and I was preparred to pay it.
> 
> ...


Stock is 16 PSI max. I agree with everything else you wrote though.


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## sedanman (Dec 10, 2010)

Big Tom said:


> When it's below 32 degrees I will use 87 most of the time, over 80 degrees it will be 93 100% of the time.


That's odd because the engine is running at the same temp no matter what the outdoor temp is once it has warmed up. About the only thing cooler will be the fuel itself, the intercooler and the intake air temp. I'd probably drop to 89 on very cold days and run 93 on hot days. We don't have 91 here but you can just mix 89 and 93 octane 50/50 for 91 octane. But no way am I going back to 87, yuck.


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## obermd (Mar 3, 2012)

The Cruze brings in outside air to help cool the intercooler. Colder air intake helps the intercooler.


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## silverls (Nov 12, 2011)

sedanman said:


> That's odd because the engine is running at the same temp no matter what the outdoor temp is once it has warmed up. About the only thing cooler will be the fuel itself, the intercooler and the intake air temp. I'd probably drop to 89 on very cold days and run 93 on hot days. We don't have 91 here but you can just mix 89 and 93 octane 50/50 for 91 octane. But no way am I going back to 87, yuck.


The engine itself is not cooler. The air fuel mixture in the chamber is cooler. And that is what makes the difference. 

Sent from my DROID BIONIC using AutoGuide.Com Free App


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## oshia86 (May 29, 2011)

Hoon said:


> Thanks man, let me know what the values look like. It's actually the turbo. At elevation where the air is thin an N/A motor draws in the same air volume, but because of the lower air density you get a lot less air mass, which has the effect of lowering compression. In a turbo motor, the effect is reduced because the turbo is forcing in an air mass closer to what you would get at sea level....meaning the octane demand is reduced in the N/A motor more than the boosted motor. I don't disagree that 87 causes knock, but there is no evidence whatsoever that it causes knock severe enough to result in any damage. According to the engineers that designed it and the accountants standing behind it, it does run fine. I personally run more octane because i'd like the added safety margin, but that doesn't mean the car wouldn't be completely "fine" on 87. I agree that 87 isn't optimal, but there is no way you can argue that anything more than 87 is needed in the overwhelming majority of situations. 87 is the proper octane for the application. You're lumping all FI engines together like they're the same thing. 1 Liter in my last car made 265hp. 1 Liter in my cruze makes about 100hp. 87 would scatter my big turbo 4G63 motor in a few seconds at 30+psi, but 400k+ Cruzes have been driving many millions of miles on 87 and to my knowledge there hasn't been one engine failure attributable to detonation. As for the quality fuel thing, the difference is the additives. Octane is the measured resistance to knock, so anything labeled 93 will perform about the same. I could never draw any conclusive results regarding knock resistance when tuning my car at 30+psi experimenting with various brands of 93, so you're not going to see a difference in a cruze on 12-14psi. Now carbon buildup over time might be affected, which might affect knock 10K miles down the road...but that's a long term side effect, not an immediate direct result.


 I'm pretty sure people here are just looking for what is optimal. Not just the minimum to get by. This is a car specific forum with enthusiasts that value such things as little as a couple more hp from using the optimal octane.


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## The_Madcat (Oct 6, 2012)

_*I don't disagree that 87 causes knock, but there is no evidence whatsoever that it causes knock severe enough to result in any damage. 

According to the engineers that designed it and the accountants standing behind it, it does run fine. I personally run more octane because i'd like the added safety margin, but that doesn't mean the car wouldn't be completely "fine" on 87.*_

The knock will do damage, hence the computer retarding the timing to protect it. With that protection, the 87 oct will suffice. But, it is not running optimally, you will still get better performance/mpg's if you run the proper octane to prevent the timing retardation.


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## giantsnation (Oct 11, 2012)

To the OP, I would simply answer your comment/question of "I don't understand why you're using 87!"http://www.cruzetalk.com/forum/10-e...i-dont-understand-why-youre-using-87-a-6.html with "I don't understand why you can't read the manual". The manual calls for 87 but not any bargain 87 - Top Tier certified 87. Thus, that is what we should be using. Of course, the manual can only suggest recommendations based on the stock configuration and my argument for using 87 is for stock Cruzes. 

As for stock Cruzes using anything other than TT 87, its money wasted. A lot of money? No. As previously posted, its not a ton of extra money but why waste money. Do some research on Octane ratings and you'll find that the majority of "benefits" of higher octane gas are mental. That's right, I said it. In a vehicle engineered for 87, putting in 93 will not yield real world benefits. 

Again, I need to stress that I'm talking about a *stock *Cruze. 

Some quick facts:
http://www.wanderings.net/notebook/Main/IsHighOctaneGasWorthTheMoney
http://mn.gov/commerce/weights-and-measures/images/OctaneFacts.pdf


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## jblackburn (Apr 14, 2012)

giantsnation said:


> To the OP, I would simply answer your comment/question of "I don't understand why you're using 87!" with "I don't understand why you can't read the manual". The manual calls for 87 but not any bargain 87 - Top Tier certified 87. Thus, that is what we should be using. Of course, the manual can only suggest recommendations based on the stock configuration and my argument for using 87 is for stock Cruzes.
> 
> As for stock Cruzes using anything other than TT 87, its money wasted. A lot of money? No. As previously posted, its not a ton of extra money but why waste money. Do some research on Octane ratings and you'll find that the majority of "benefits" of higher octane gas are mental. That's right, I said it. In a vehicle engineered for 87, putting in 93 will not yield real world benefits.
> 
> ...


Drive a stock manual 1.4T Cruze in 100+ temps in the summer with 87, and tell me I'm wasting my money putting a higher octane in it.  It drives like poop.


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## titan2782 (Nov 4, 2011)

giantsnation said:


> To the OP, I would simply answer your comment/question of "I don't understand why you're using 87!" with "I don't understand why you can't read the manual". The manual calls for 87 but not any bargain 87 - Top Tier certified 87. Thus, that is what we should be using. Of course, the manual can only suggest recommendations based on the stock configuration and my argument for using 87 is for stock Cruzes.
> 
> As for stock Cruzes using anything other than TT 87, its money wasted. A lot of money? No. As previously posted, its not a ton of extra money but why waste money. Do some research on Octane ratings and you'll find that the majority of "benefits" of higher octane gas are mental. That's right, I said it. In a vehicle engineered for 87, putting in 93 will not yield real world benefits.
> 
> ...




Originally the manual said 87 and a lot of people go based on that, but I believe someone mentioned that GM updated the manual to specify premium. Someone correct me if i'm wrong on that. 

Obviously you've never built a car and you're not a gear head. Being designed to run 87 and being able to run on 87 are not the same thing. 

I'll give you a chance to prove me wrong though. Grab a data cable and do some data logging. Get in some normal driving as well as some good WOT pulls in 3rd, 4th and 5th and do this with a tank of 87 and a tank of 91. Using the data logs, show me the lack of real world benefits. Now do this again in the summer.

Edit: Further more, I don't want to hear anything "technical" unless you provide some logs as backup.


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## titan2782 (Nov 4, 2011)

My manual says "Use regular unleaded gasoline with a posted octane rating of 87 or higher." and the wording there is to indicate that you should not be using a fuel with a rating less than 87. 87 being the MINIMUM octane. Keep in mind that states like Colorado have lower than 87 octane. I've seen 85 and event 83 1/2 (was at a gas station here in so cal actually on an old road) and no where does it say that 87 is the recommended octane. 

BTW you can find out if your gas station is "Top Tier": Top Tier Gasoline


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## bodeis (Jan 28, 2012)

KRD = FUEL RATING OCTANE NO. 91 91 OCTANE FUEL(KRD) is listed as an RPO for my 2012 Chevy Cruze eco. Not sure what it means but ive only run 91 or higher in mine.


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## obermd (Mar 3, 2012)

The Cruze can run on 87 octane. However, when it does this it spends a lot of time retarding engine timing to avoid engine knock. Anytime you retard the engine timing for this you are literally throwing energy away because the cylinder ignition spark isn't synced with the pistons for optimal pressure. Increasing the octane reduces the amount of knock, thus not throwing away energy. Your car's performance as well as the MPG will improve as a result. The question then becomes "Am I getting enough additional MPG to offset the increased pump price?"


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## titan2782 (Nov 4, 2011)

Here is a good article to drive the point home

2011 Chevrolet Cruze LTZ: The Ultimate Hot Weather MPG Test - Regular vs. Premium



> "So what?" you say. "Premium is more expensive."
> Is it?
> 87 octane: $3.60 per gallon (average), $645.01 for 4,381 miles
> *14.72 cents per mile*
> ...


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## HisandHers (Aug 18, 2012)

I also run 87 in mine beacuse the spread is 40 cents from 87 to 91 in my area.I use about 12 gallons a week so that adds up pretty fast.


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## ErikBEggs (Aug 20, 2011)

titan2782 said:


> This is in response to a ton of previous posts about the trifecta tune and 87 octane and also to the recently announced budget tune.
> 
> I never understood why you would want to spend the money to get extra performance but you won't spend the money on the proper octane fuel to make sure you get that performance. Let's do some math.
> 
> ...


One thing Californian's and New Yorkers must consider is that our fuel situation is NOT the same as other states. Our REDICULOUS gas prices are due to REDICULOUS state fuel tax, which is a product of our state's having high population and a large amount of non-tolled roads and highways. Therefore, the gas tax is needed to maintain these roads. That is why the difference in Premium Grade fuel and Regular fuel for us is never more than $.25-$.30 / gal., which is less than 10%. Our high prices are almost exclusively because of taxes! Well guess what... some states charge a HEFTY price premium for using premium simply because they can get away with it. In Delaware I witnessed a $.70 / gal price premium between Premium and Regular Gas, which was approaching 20% cost! So for us Premium makes much more sense. When I tripped to Michigan 2 weeks ago this is how it looked:

Michigan: 87: $3.78-$3.82 / 93: $4.32-$4.35 New York: 87: $4.09-$4.11 93: $4.27- $4.30

Which one makes more sense in that case?

Try this. Go to New Jersey then drive into New York State. New Jersey gas is about $.35-$.37 / gal cheaper than New York gas. Guess what the gas tax is? New Jersey - $.13 / gal, New York $.50 / gal. Yep. All Northeastern states get their fuel from the same refineries. Taxes are the difference. In most cases, taxes will not effect the price premium itself for using premium fuel.


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## bodeis (Jan 28, 2012)

Im in the thumb in Michigan, around here its 20-30 cents more for premium. Depends though, local sunoco sells 87, 89, 91, and 93. The 93 is about 40 cents more per gallon. I typically run shell 93 which is about 30 cents higher. Car never takes more than 10.5 gallons and i fill up every two weeks. So for me personally, a couple dollars every two weeks isnt a concern.


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## titan2782 (Nov 4, 2011)

@bodies are you running a tune?

I think this thread is going away from the point which is Cruze owners who want performance but don't want to use premium fuel.


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## jblackburn (Apr 14, 2012)

titan2782 said:


> @bodies are you running a tune?
> 
> I think this thread is going away from the point which is Cruze owners who want performance but don't want to use premium fuel.


I'll admit, I was mad when I bought the Cruze to run on regular gas after owning a turbo car before that would only run well on 89-93. I wanted a car that got better gas mileage and DIDNT need special care.

But I guess now that I've accepted that, I'm much happier with it vs something like a Civic.


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## titan2782 (Nov 4, 2011)

jblackburn said:


> I'll admit, I was mad when I bought the Cruze to run on regular gas after owning a turbo car before that would only run well on 89-93. I wanted a car that got better gas mileage and DIDNT need special care.
> 
> But I guess now that I've accepted that, I'm much happier with it vs something like a Civic.


I came from an 06 Kia where I was putting in the cheapest 87 I could find (Arco). Getting the Cruze was buying a top end Cadillac! The guy was showing me all the features and I was like, no, I just want a cheap base model. I flipped when he said it was all standard! They gave me a tank of 91. I didn't think anything of it. I didn't know the car had a turbo until a few days later! I was planning to run 87 but my wife had put in a tank of 89 by mistake and it ran like crap. I learned it had a turbo and after my excitement calmed down I vowed to treat it as I would any turbo motor.

That's no joke, I did not know it had a turbo.


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## giantsnation (Oct 11, 2012)

titan2782 said:


> Originally the manual said 87 and a lot of people go based on that, but I believe someone mentioned that GM updated the manual to specify premium. Someone correct me if i'm wrong on that. [/QUOTE]
> 
> You are incorrect on that. No such update to speak of and the online manual says 87 octane - http://www.chevrolet.com/content/dam/Chevrolet/northamerica/usa/nscwebsite/en/Home/Ownership/Manuals%20and%20Videos/02_pdf/2k13cruze.pdf
> 
> ...


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## jblackburn (Apr 14, 2012)

titan2782 said:


> I came from an 06 Kia where I was putting in the cheapest 87 I could find (Arco). Getting the Cruze was buying a top end Cadillac! The guy was showing me all the features and I was like, no, I just want a cheap base model. I flipped when he said it was all standard! They gave me a tank of 91. I didn't think anything of it. I didn't know the car had a turbo until a few days later! I was planning to run 87 but my wife had put in a tank of 89 by mistake and it ran like crap. I learned it had a turbo and after my excitement calmed down I vowed to treat it as I would any turbo motor.
> 
> That's no joke, I did not know it had a turbo.


Sure doesn't drive like there's a turbo under there - the powerband is pretty consistent. I had a nice-ish car that actually had something other than a few hamster wheels under the hood, so I saw it as justified for that one. But man, did it eat gas. After that, I just wanted a fuel-efficient, no-frills, reliable car.

Aside from really hot weather, though, my *stock* Cruze seems to run fine on 89 octane so that's what I'll stick to. It has enough power for most needs and nothing more.

With its track record so far, the warranty is something I definitely want to keep around, so I won't be tuning this car.


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## obermd (Mar 3, 2012)

jblackburn said:


> Sure doesn't drive like there's a turbo under there - the powerband is pretty consistent. I had a nice-ish car that actually had something other than a few hamster wheels under the hood, so I saw it as justified for that one. But man, did it eat gas. After that, I just wanted a fuel-efficient, no-frills, reliable car.
> 
> Aside from really hot weather, though, my *stock* Cruze seems to run fine on 89 octane so that's what I'll stick to. It has enough power for most needs and nothing more.
> 
> With its track record so far, the warranty is something I definitely want to keep around, so I won't be tuning this car.


The turbo is the reason the power band is so wide and flat.


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## obermd (Mar 3, 2012)

titan2782 said:


> ... Again, lets keep in mind I'm talking about a stock Cruze. But they are in fact the same. Drive the car as it is intended - economy sedan, not sports sedan and 87 octane will do you just fine.


I have a stock 1.4T engine other than spark plug gaps, which I set to the original GM Spec for this car/engine. In the summer this car is undrivable with 85 or 87 octane (Denver). It requires 91 (Denver). Anything less and the throttle feels like there's a cylinder misfiring.


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## ErikBEggs (Aug 20, 2011)

To answer the OPs question: people use 87 because it is safe to and GM says you can run it so why pay extra? The end. There really is no other need for discussion as to if a stock Cruze runs 87 or not.


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## jblackburn (Apr 14, 2012)

obermd said:


> The turbo is the reason the power band is so wide and flat.


Agreed - I love small low-pressure turbos.

But high-pressure turbo cars are an entirely different beast. Lots of lag, then LOTS of power when it picks up.


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## giantsnation (Oct 11, 2012)

ErikBEggs said:


> To answer the OPs question: people use 87 because it is safe to and GM says you can run it so why pay extra? The end. There really is no other need for discussion as to if a stock Cruze runs 87 or not.


:sigh:


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## titan2782 (Nov 4, 2011)

ErikBEggs said:


> To answer the OPs question: people use 87 because it is safe to and GM says you can run it so why pay extra? The end. There really is no other need for discussion as to if a stock Cruze runs 87 or not.


Which is exactly why I'm talking about owners who want performance (tunes, parts, mods) but won't spend a tiny bit extra (statement not true in some areas) for proper octane to take full advantage of said changes.

Want to run your stock cruze on 87, go for it. Again, no need to discuss it.


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## giantsnation (Oct 11, 2012)

titan2782 said:


> Which is exactly why I'm talking about owners who want performance (tunes, parts, mods) but won't spend a tiny bit extra (statement not true in some areas) for proper octane to take full advantage of said changes.
> 
> Want to run your stock cruze on 87, go for it. Again, no need to discuss it.


I agree with you on this 100%. 

Should we try to doa little comparison on which mods and best octane rating for each (not sure if its been done). For example, I would personally would run 93 octane (or 91 if 93 is not available) with a CAI and trifecta tune. However, I would think 89 would suffice for just a SRI. Just curious.


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