[jblackburn]

I've experimented with 87, but the car doesn't like it a whole lot once temps get warmer outside. It bogs from a standstill quite a bit with the AC on. I have found that it likes 87 from the Exxon up the road, but other times I've tried it, it ran like complete crap on other brands. Hesitation was seriously bad.

I usually use 89 octane and feel that my (untuned) Cruze performs just fine on it, or in the peak of summer when it's 90-100 out, I'll use 93. Same reason...that bogging with the AC on is due to timing being pulled because of pre-detonation. It can be downright dangerous trying to pull out into an intersection and the car just won't respond like it normally does.

For me, there is no noticable MPG difference between 89 and 93, but there is a ~4 highway MPG difference between those crummy 87 tanks and 89.

 

[jblackburn]

Well I used to put 87 octane in my 05 cavalier when I had it 2 years ago and I noticed it helped the mpg a little. Not by much but it did. I was going to fill my car up today with the 87 octane but then I was thinking.."Im not sure how well it will run for sure or if my mpg will increase or decrease". Can anyone tell me with their knowledge and/or experience, in comparison, which fuel burns the best to get better fuel economy? I want to see how much more mpg I can get out of my LT. I think right now, im getting 38-39 mpg going right at the speed limit=]

Try a tank of each on your car and see how it does. It mostly depends on your driving...I'm a bit heavy-footed and so I'm sure I'm throwing away MPG on 87. The car feels a bit slower, so I push it a bit harder. If you drive conservatively all the time, there may not be a difference.

Turbo engines aren't a fan of low octane gas, so they pull timing and decrease power when they detect knock. This happens often on the Cruze - you can often feel little "pulses" in power between 2000-3000 RPM. Every time that happens, you're throwing away power/MPG.

87 octane does contain slightly *more* power per unit than higher octanes, BUT it has less knock resistance. For engines such as your Cavalier that do not benefit from higher octane by increasing timing advance, they will get the best MPG on 87 since they able to use the engine's full potential on that gas.

93 octane doesn't give you more power persay, but it lets higher-performance engines run closer to their maximum potential by not pre-igniting.

 

[jblackburn]

Anyone have a Phillips 66?

Haven't seen those since the 1990's!

 

[jblackburn]

If I go an hour south, gas prices drop by 30 cents/gallon.

The joys of living near a big city...

 

[jblackburn]

Question for those of you living in the flat parts of the US. For driving across Kansas, Illinois, and Indiana on I-70 in an ECO MT, what octane would you recommend? Basically I'm going to be sitting on Cruze control for hours on end. Central Missouri is hilly enough that I'll run 91 or higher depending on what's available. Northeast of Columbus, Ohio I'll run 91 or higher to handle the hills of the Appalachian mountains.

It does perfectly fine on 89 at lower elevations with no hills. Heck, even with hills, it does fine @ 3000 ft.

Course...depends how hot it is when you make the trip. If it's above 90, I step up to premium. Other than that, gas is over $4 here for premium and I refuse to pay that.

 

[jblackburn]

Slightly less in premium. Not a huge difference in BTUs. Usually premium contains a higher % ethanol, which helps to reduce knock.


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[jblackburn]

Depends on if both grades have 10% ethanol. Around me most stations premium is 91 octane no ethanol, so it actually has a few thousand more BTU per gallon.

Ah...it's UP TO 10%. Regular is more like 5-7%, while premium is 10% in most places.




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