· Premium Member
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
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.
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.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:
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.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?
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.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?
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....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?
yes you should.So after reading this discussion, I should put 91 in my cruze when I pick it up???
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....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.
The email states it is not recommended to use any octane above 91, not that it recommends 91.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.