# What fuel to run... 87 octane vs 93 octane... EDIT (or E85?)



## v8sten (Aug 24, 2017)

I have a stock 2018 Cruze LT, I also have HPTuners. I pulled a log on 87 octane and logged 93 octane. The differences are not surprising, but pretty interesting. I tried logging different scenarios and my some of my normal driving habits. Brake boosting from a roll and from a dig, easing into the throttle, smashing the throttle and basic cruising. Judging off these result. It looks like 93 it is.


Here ia a log on 87 Octane, look at all that knock retard........










Not much to correct with the 93 Octane tune


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## Eddy Cruze (Jan 10, 2014)

So 87 is acceptable?


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## obermd (Mar 3, 2012)

Given those two charts I think I'd be running at least 89.


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## PolarisX (Dec 17, 2017)

Eddy Cruze said:


> So 87 is acceptable?


I'd say soild no. 6º of retard is not conducive to long engine life. On top of that, your mileage and power go to crap because the engine is yanking timing and boost out try to save it.


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## PolarisX (Dec 17, 2017)

Great chart.

I'd like share these in a few different places, are you okay with that?


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## v8sten (Aug 24, 2017)

PolarisX said:


> Great chart.
> 
> I'd like share these in a few different places, are you okay with that?


Go for it


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## v8sten (Aug 24, 2017)

PolarisX said:


> I'd say soild no. 6º of retard is not conducive to long engine life. On top of that, your mileage and power go to crap because the engine is yanking timing and boost out try to save it.


mine doesnt pull any boost on 87, it just knocks. 

launches @ 10-11 psi 
peaks @16 psi
tapers to 13 psi on the big end

does that both on 87 or 93


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## PolarisX (Dec 17, 2017)

Wow, I figured it would pull boost. It's starting to become clear now why certain years eat pistons.


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## v8sten (Aug 24, 2017)

PolarisX said:


> Wow, I figured it would pull boost. It's starting to become clear now why certain years eat pistons.


seems pretty clear cut


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## Pumpkin pie man (Feb 23, 2020)

Great job. Thanks for this!


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## v8sten (Aug 24, 2017)

Pumpkin pie man said:


> Great job. Thanks for this!


No problem, I couldnt find any real info on this subject and figured other people were wondering the same. Mine will never see anything below 93 octane.


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## Thebigzeus (Dec 2, 2018)

v8sten said:


> No problem, I couldnt find any real info on this subject and figured other people were wondering the same. Mine will never see anything below 93 octane.


Well depending on where you drive... you may not have a choice. Some places I've only seen 91.


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## v8sten (Aug 24, 2017)

Thebigzeus said:


> Well depending on where you drive... you may not have a choice. Some places I've only seen 91.


Well this is where a little common sense applies


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## Thebigzeus (Dec 2, 2018)

v8sten said:


> Well this is where a little common sense applies


Tell me more lord vader


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## v8sten (Aug 24, 2017)

well if you cant figure it out on your own............ i dont know what to tell you


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## gacl (Jan 22, 2019)

I have a question, does using the L mode on the shifter, and keeping the RPM's above 2,000 when going up hills and giving the car gas reduce knock? I know its common for this car to go up hills and lug the engine by taking an incline in 6th gear at 1,450 RPM and I always force it to downshift. Would I still be knocking in this case? Kind of new trying to learn


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## v8sten (Aug 24, 2017)

in that part of the map, yes. i was just showing that running 87 octane, it doesnt matter what the scenario is, its gunna knock, no matter what. its best to run super unleaded in these cars.


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## Iamantman (Sep 24, 2018)

gacl said:


> I have a question, does using the L mode on the shifter, and keeping the RPM's above 2,000 when going up hills and giving the car gas reduce knock? I know its common for this car to go up hills and lug the engine by taking an incline in 6th gear at 1,450 RPM and I always force it to downshift. Would I still be knocking in this case? Kind of new trying to learn


L mode won't make a difference unless you limited the number of gears but what I do sometimes is if I see a hill or crest and I know it will be a scenario where the engine might lug (say higher gear @ 30mph or so) I intentionally punch the gas a bit to downshift my transmission and go up the hill in a lower gear at higher rpm to limit this. 

I run 93 in my car so I'm not as concerned but I'm still a hyper weirdo with my car so I don't want to take any chances.


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## v8sten (Aug 24, 2017)

I looked over the logs and noticed that my IDC (Injector Duty Cycle) is only at 11% max. The timing hovers around 5 to 10 degrees under boost. There is a lot of room to grow as far as power and efficiency. Then I pulled the tune on my 2018 Cruze. The Flex Fuel is "enabled" .......... So are the Commercial Vehicles, flex fuel cars? I cannot find any stickers, or any info on the car itself. like "only run premium fuel" sticker or anything. The fuel cap is black and not yellow. There is nothing stating what fuel to run. But everything I have seen in my car is telling me that its a flex fuel car.


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## Eddy Cruze (Jan 10, 2014)

The Chevrolet CRUZE runs perfectly fine on 87 octane gas with full boost available. The only exception is during the hotter Summer months, and with some early models. We've had 1000's of posts here on the subject


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## v8sten (Aug 24, 2017)

Eddy Cruze said:


> The Chevrolet CRUZE runs perfectly fine on 87 octane gas with full boost available. The only exception is during the hotter Summer months, and with some early models. We've had 1000's of posts here on the subject


The log i pulled says otherwise


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## Eddy Cruze (Jan 10, 2014)

v8sten said:


> The log i pulled says otherwise


One Log, One, Tune, One Car


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## obermd (Mar 3, 2012)

Eddy Cruze said:


> One Log, One, Tune, One Car


His log was on a stock tune. I'd have to agree with him that the log says don't run 87 octane.


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## v8sten (Aug 24, 2017)

Eddy Cruze said:


> One Log, One, Tune, One Car


Its your car, you run what ever fuel in it you want. I looked specifically for this info and found nothing. So I took it upon myself to figure it out and provide this info to the masses. But when you wind up having a cracked piston due to running an inadequate fuel, remember this thread.

EDIT

I just added a burst knock config to my channels. Its not showing any burst knock, so that means it is actual knock. The timing pulled it reactionary, meaning.........


it knocks
knock sensors pick it up
knock sensors inform ecm that there is knock
ecm pulls timing out after the fact that the knock has already happened

Eddy if you dont get that, i cant help you


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## v8sten (Aug 24, 2017)

Now E85 subject. I just added 2.5 gallons of E85 to my almost full 93 (E10) tank. It read 9.8% before and did not change from that 9.8%. So that tells me that it is virtual and not actual. The flex fuel is turned on for that 9.8% and this car, from the factory is tuned to run on 93 (or 91) octane fuel.

I hope this helps everyone out, if you dont agree with me, frankly i dont care, have fun blowing your motor up.


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## Eddy Cruze (Jan 10, 2014)

obermd said:


> His log was on a stock tune. I'd have to agree with him that the log says don't run 87 octane.


I'm not too worried about Piston failure and even if there was a failure I am covered. I also use Safeway or Kroger non Top Tier gas with no 2nd thoughts


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## PolarisX (Dec 17, 2017)

v8sten said:


> Now E85 subject. I just added 2.5 gallons of E85 to my almost full 93 (E10) tank. It read 9.8% before and did not change from that 9.8%. So that tells me that it is virtual and not actual. The flex fuel is turned on for that 9.8% and this car, from the factory is tuned to run on 93 (or 91) octane fuel.
> 
> I hope this helps everyone out, if you dont agree with me, frankly i dont care, have fun blowing your motor up.


I think part of that is why these cars seem to actually do better with some ethanol content instead of just octane grade. I've seen a few forums where people report better luck on 93E10 vs 93E0 fuel. I also agree that anyone running 87 in the LE2 is just leaning on those knock sensors so hard it hurts. Your charts proved what I've seen with torque since 2017, a ton of knock retard on the stock tune with 87, and minimal but still slight on 93 octane.

I've only got to play with 87 briefly as I moved our 2016.5 to 93 ASAP, and our hatch never saw 87 octane except what the dealer put in it. That was the only time I've ever had a loss of power event, with an audible crackling sound.

It also seems a lot of information from Gen1 cars keeps getting applied to Gen2 when it has no business at all. They don't share anything at all, but I see it constantly here and Reddit. Constantly having to remind people of this.


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## PolarisX (Dec 17, 2017)

Eddy Cruze said:


> The Chevrolet CRUZE runs perfectly fine on 87 octane gas with full boost available. The only exception is during the hotter Summer months, and with some early models. We've had 1000's of posts here on the subject


Yeah for Gen1 cars, maybe.

There is a distinct lack of this information for Gen2 owners, besides the 16.5 and 17 owners who shattered ring lands, they learned that the hard way. I looked hard for this information like OP and got nothing but unrelated posts for Gen1 cars. That is what got me to get Torque / OBD2AA working on my head unit to monitor timing and KR on a regular basis.

Remember the Gen1, and Gen2 cars might as well not even share the same name, nothing is the same.


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## Eddy Cruze (Jan 10, 2014)

Points well taken. I have no knowledge with the Gen 2 CRUZE and should not post here


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## v8sten (Aug 24, 2017)

PolarisX said:


> I think part of that is why these cars seem to actually do better with some ethanol content instead of just octane grade. I've seen a few forums where people report better luck on 93E10 vs 93E0 fuel. I also agree that anyone running 87 in the LE2 is just leaning on those knock sensors so hard it hurts. Your charts proved what I've seen with torque since 2017, a ton of knock retard on the stock tune with 87, and minimal but still slight on 93 octane.
> 
> I've only got to play with 87 briefly as I moved our 2016.5 to 93 ASAP, and our hatch never saw 87 octane except what the dealer put in it. That was the only time I've ever had a loss of power event, with an audible crackling sound.
> 
> It also seems a lot of information from Gen1 cars keeps getting applied to Gen2 when it has no business at all. They don't share anything at all, but I see it constantly here and Reddit. Constantly having to remind people of this.


We have 92 Octane with 0%E at Bucees right down the road. That sh!t is expensive. Not worth the extra cost IMO. Thats why I didnt even try it.


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## 6speedTi (May 18, 2018)

Several things to consider. 
Altitude where you drive.
Temperature and barometric pressure. 
Quality of fuel used.
Driving habits.
I've done my fair share of reading on this subject. Especially tuners running different octane levels and stock and tuned engines. Also one tuner on the chevy sonic site ran with all knock sensors turned off with various octane levels. Then he ran it stock.
To avoid a lengthy post the 1.4 liter turbo on 87 was knocking like a woodpecker. The best octane level was about 90 to 91 to avoid the knocking. Knock sensors were going crazy with 87 octane to protect the engine.
So my opinion and recommendation is to use at least a mid grade 89 or higher with a stock tune.
What you decide is up to you. It's your vehicle to do as you see.


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## v8sten (Aug 24, 2017)

6speedTi said:


> Several things to consider.
> Altitude where you drive.
> Temperature and barometric pressure.
> Quality of fuel used.
> ...


if there is no knock, or minimal knock on the stock tune, there is no need to desensitize the knock sensors. that was not needed to figure that out. Also the audible knock head while driving on 87 octane is a dead giveaway. That will happen with the knock sensors fully functional, as i stated in post #24. It still knocks with 93 octane, minimal, but it still knocks. I highly recommend 93 octane if at all possible.

EDIT

Me personally I live just south of Houston where the air is great most of the time, not all the time, but most of the time.

3/18/20 @ 1528 (3:28 PM)
temp: 80 deg F
humidity: 67%
elevation: 9'
pressure: 30.05 in (14.759 psi)
DA : 1512 ft (crappy)

The air is shitty today but this is as bad as it gets. So other parts of the country can only be worse.

Driving Habbits: On my logs I try to go through all different kinds of driving habbits and scenarios. I cleared the Long Term Fuel Trims to take that variable out of the equation.


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## Snipesy (Dec 7, 2015)

I always run 87 octane in my V6. No turbo life is nice.


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## -loki- (Dec 13, 2019)

93 top tier gas all the time... 87 turns the car into a retarded pinging monster on the stock tune.


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## CRUZE-66 (May 4, 2019)

A few things I found from owning my '17 Premier hatch for the last 2 years, is with the 87 octane that came in the car with the dealer- (I did asked them what gas they put in and I told them in a polite way I was essentially disappointed) -the engine/trans would barely respond until nearly 1/2 throttle. I was guessing it was taking out timing, holding back boost, enriching the fuel all the while it would hold the trans in a high gear. Then what seemed about 1/2 pedal, the trans would downshift, revs rise and boost would kick in. Then it felt pretty good.

But man just driving around normal and wanting to to give it a bit of juice here and there seemed like the car would rather pull teeth than get up and go. In a nutshell, the pedal to throttle directness was nonexistent. It felt horrible and I figured it was how the car was engineered and it was disappointing to say the least. 

However, me knowing these cars LSPI issues for that 1st 87 octane tank I did use the gas pedal like an egg was on it _most_ of the time. After I had about a full tank of shell 93 octane, the car felt like it did pull harder, had a bit better throttle response and kicked the trans down with not as much prodding. So at least now I was satisfied somewhat that it wasn't a total engineering mess up.

...Then as the weather got hotter I wanted to give a gallon of E85 with the rest 93 gas(costco now) a try since I see comments about how our Cruzes can lay down in real hot weather. Not mine. I had it pulling at low 90s temps like it does at 40F. I mean it would just pull up to 90mph right NOW with no drama, super smooth and steady as I could imagine.

...Then after that I reset the computer since I had my 15% ethanol/93 octane mix. I thought it might drop some bad habits in the fuel table like retarded timing and richer mixtures. It did. After getting any where from just under 33 mpg in the winter to as high as 37mpg in the summer, I did 41 mpg on the first full tank of that fuel ratio. The rest of summer 39 was the lowest I got. My last winter tank was 36. That's doing the numbers by hand. On my Cruze the MPG counters are usually 1mpg too generous . My Cruzes' lifetime MPG on the trip B is 36.6 I never reset the trip B. 

Better still the throttle almost feels like it's connected to a wire now. and the trans will downshift quite easily. Nothing really different from the automatics from the less strict MPG quotas from decades ago. Which to me is strange b/c you'd think on the LSPI cars with 87 octane they'd want to to get it revving while keep the timing retared and boost lower so you can get the car moving without risking it blowing. Instead their strategy seems to make it worse all the while the car goes nowhere.

So lastly I want to thank V8sten for his fuel tables and backing what I thought I was experiencing with his data. Also to others who have given excellent advice and input such as jblackburn, MP81, PolarisX and lamantman. There's others but those quickly come to mind.


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## v8sten (Aug 24, 2017)

I bought my 07 Z06 from a Chevy dealer, They went to go put gas in it and I asked before they left........ "What kind of gas do you put in there?" They said regular. I said HELL NO!!!!! You are not putting 87 in my new Z06!!!!! 

So that is just basic operation for dealerships, apparently. 

In my Cruze I did notice audible pinging coming from the motor and I knew immediately what it was. To further expand on the E85 thing, I have a stock tune from a 2019 Premier Cruze (Flex Fuel) and it is far different from what is in my car when I did a comparison in between the 2 files. Same tables, just adjusted differently.


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## CRUZE-66 (May 4, 2019)

I knew almost certainly they would fill it with 87 but from what I can tell, GM actually recommends 91 octane for these cars with 87 as the minimum rating. I thought that maybe the dealer would do the right thing. No such luck. Just like with the oil filters. I knew I had 100s of miles of driving to drain out the tank until I could put in the proper fuel. And this is why I never went back to the dealer or any dealer since I drove it off the lot. They can keep their crappy oil filters and oil and I would have prefered them to give me a nearly empty tank of gas instead of 87.

After the 2 year _bad_ service agreement is over, I may go to get some issues like the "can't find remote key fob crap" to get fixed. I think that should be about it.

In a Z06 87 octane is 100% unacceptable.

And by the way, in the peak of summer the E85 would get bumped *up * to 2 gallons to a tank along with the 93. With that ratio the car runs really nice in hot weather.


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## v8sten (Aug 24, 2017)

Its not showing any "lean knock" but Im just going to run 93 in mine from here on out. Everything showed me that is the fuel to run in these cars, least amount of knock, less damage to the fuel system and best fuel mileage


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## JoeyHono (Jan 25, 2019)

WOW, this is a great thread, going super from now on, my dealer told me reg gas as well


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## -loki- (Dec 13, 2019)

Put in top tier 93 on a near empty tank, you'll notice a difference


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## WillL84 (Aug 5, 2019)

-loki- said:


> Put in top tier 93 on a near empty tank, you'll notice a difference


I did that this past Tuesday. Been running 87 since I bought it in August. Put 93 in it Tuesday afternoon. Have ~150 miles on it now since and don't notice any difference.


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## obermd (Mar 3, 2012)

WillL84 said:


> I did that this past Tuesday. Been running 87 since I bought it in August. Put 93 in it Tuesday afternoon. Have ~150 miles on it now since and don't notice any difference.


It really depends on your driving habits and environment. Try the same thing in the middle of the summer and you may notice a difference. Some members run 87 in the winter and 89 or 91 in the summer because of heat soak.


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## -loki- (Dec 13, 2019)

I noticed. Ran smoother, throttle more responsive... never ever have I heard of turbo cars running 87.... you always run high octane because it's easier to control the ignition and detonation. Run 93 mixed with 110 leaded sunoco in my R6... ran 87 in it after getting it wired and it barely wanted to start let alone run worth a $h17. When adding compression to an engine via f.i. or overall motor build... you want to control the BooM... lower octane explodes easier making it harder to control... higher octane gas resists detonation those making it easier to control. That's why you see reduction in KR on those maps.

Now... with meth or water injection and a hell of a front mount and tune you might be able to get it to run on 87 like that and make numbers... but it won't be very safe.


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## v8sten (Aug 24, 2017)

What started this for me was when I bought it a few weeks ago. The dealership filled it up with 87, I didnt think anything of it. I heard some clattering when the engine was under a load. I thought to myself, "Is this pos detonating?" So i hooked up my hp tuners and pulled a log. Sure enough it is. I looked for anything stating what fuel to run and came up with no definitive answers. So i ran that tank almost completely empty and filled up with 93 and pulled another log. Those are what you see in thew original post. I was positive that other people had the same question i did, so why not start a thread.

That being said. I have noticed that GM prefers to tune most of their vehicles on the lean side with a lot of timing and rely on "Burst knock" to take care of the knocking issue. Burst knock is a predictive knock timing control, based on your driving habbits, over time. These Cruze's do not have any burst knock programmed in at all, so it relies on the knock sensors. I have covered the sequence of events in an earlier post. So all you die hard 87 octane people, dont complain when your engine isnt covered under warranty for "using inadequate fuel". Just a precursor warning, I can see that happening.


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## -loki- (Dec 13, 2019)

Somewhere on the forum I read that these engines were designed for the foreign market and then brought to America.


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## v8sten (Aug 24, 2017)

-loki- said:


> Somewhere on the forum I read that these engines were designed for the foreign market and then brought to America.


Probably, wouldnt doubt it


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## Barry Allen (Apr 18, 2018)

There is a fuel station near me that has a pump selling different ethanol blends with selections for E10, E15, E30, E50, and E85. I owned a prior gasoline vehicle (Hyundai Accent) that had 11:1 compression, which I considered to be pretty darned high for a stock vehicle. I used to fill that vehicle with E30 fuel because it was about 94 octane, and that was the threshold where the CEL would not illuminate (E50 would throw a CEL). I got decent results with that vehicle: power was OK (if you want to call 100hp "OK") and fuel economy was only about 2-3% less on average than running straight gasoline. The cost discount for running E30 was right in the sweet spot to where it saved money.

If you have a fuel station near you that has a similar blender pump, try E30 fuel


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## v8sten (Aug 24, 2017)

and im willing to bet if you were to put a wideband on there it would be on the lean side, which causes knock. did you pull a log like i did with running e30? if not how can you know for sure if it is good for your motor or not? I wanted to definitively know what fuel to run in my car, and i wanted data to show this. "running OK" is not definitive data. My car ran "OK" with 87 octane but the data log shows otherwise. 

Story short, dont make claims without actual data. I can show my results, and go further into detail if needed. That is the whole point of this thread.


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## -loki- (Dec 13, 2019)

I think he was referring to the Hyundai running the E30...


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## Drew's Cruze (Jul 31, 2015)

89 octane here since new (4.5 years), 25.95 mpg avg, mostly in horrible Chicago traffic, no knocks etc., but no tuners or hooning either


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## Barry Allen (Apr 18, 2018)

v8sten said:


> and im willing to bet if you were to put a wideband on there it would be on the lean side, which causes knock. did you pull a log like i did with running e30? if not how can you know for sure if it is good for your motor or not? I wanted to definitively know what fuel to run in my car, and i wanted data to show this. "running OK" is not definitive data. My car ran "OK" with 87 octane but the data log shows otherwise.
> 
> Story short, dont make claims without actual data. I can show my results, and go further into detail if needed. That is the whole point of this thread.


If you have a fuel station near you that has a similar blender pump, try E30 fuel.


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## v8sten (Aug 24, 2017)

we have .......
E0 89 octane
E10 87, 89, 93 octane
E85 (usually E65-E87 depending on station)


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## Barry Allen (Apr 18, 2018)

v8sten said:


> we have .......
> E0 89 octane
> E85 (usually E65-E87 depending on station)


Fill the tank to 3/4 with 89 octane and then fill the rest with E85. That should get you to about E30 to watch the results.


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## Barry Allen (Apr 18, 2018)

CRUZE-66 said:


> GM actually recommends 91 octane for these cars with 87 as the minimum rating.


The owners manual appears to say nothing about "recommended" higher octane fuels.


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## CRUZE-66 (May 4, 2019)

Here you go Barry Allen:










Using 91 octane- I may have found something.....


I work as a parts guy at a Chevy dealer, and I also have a 2017 Cruze. There have been issues with detonation (pinging) damaging pistons. We just had one towed in Monday with a damaged piston. I can see Chevy eventually releasing some type of recall/service bulletin similar to what's going...




www.cruzetalk.com





And lets face it, GM wants to sell cars and saying near entry level compact sedans should use 91 is not in the business plan. At least in this country.


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## JunkieXL (Nov 24, 2017)

I've always ran Shell 93 octane (and Amsoil Signature Series full synth) since I drove it off the lot. I'm at 31k miles now. The manual says 87 is fine though, but these small TC engines really need the added octane to prevent pre-detonation which is a byproduct of tiny TC engines.


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## CRUZE-66 (May 4, 2019)

More evidence that 91 octane is really what GM would like to see in these cars is in this article. 










GM Once Again Calls For Premium Gasoline To Become New Standard


GM vice president of global propulsion systems Dan Nicholson said the change could net a 3 percent increase in fuel efficiency.




gmauthority.com





And the timing of the article is less than two months before the new rating for motor oils (SN+) were about to hit the shelves. And what engines were GM having the most problems with in regards to detonation and LSPI? The 1.5 and 1.4 litre direct injected turbos. 
Unfortuneately GM didn't get the minumum standard for octane raised. That would take too much of the cash cow from Big Oil. But they got the update on SN oils to the SN+ rating.


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## Barry Allen (Apr 18, 2018)

This might be a handy reference chart:










Oak Ridge National Lab did testing of various ethanol blends to test octane ratings.

There is some conflict with what is available at a lot of gas pumps. ORNL appears to have tested regular 87 octane gasoline that has a 0% ethanol content and then added pure ethanol to bring the blends to exact or almost exact blends. All the pumps around me have 87 octane fuel that already contains up to 10% ethanol, so it's likely refinery blending done with sub-octane (below 87) gasoline knowing that the 10% ethanol added will bring it up to or past 87 octane. E15 gasoline near me is sold as 88 octane fuel and it's able to be used in basically any newer vehicle without issues. Other experience has shown that E30 is able to be used in newer vehicles without issues, as well.

Near me, the only ethanol free fuel you can usually find is 91 octane and it sells at quite a price premium. Thus, it's hard or impossible to find 87 octane fuel that is free of ethanol and then try to add enough E85 fuel to bring it up to a premium octane blend for cheaper than buying premium fuel from the pump. Still, it might be worth trying for some people.


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