It'll definatley run better. I dunno about a big mpg increase. Try it a few tanks and see if it stays up there.

I've noticed a big performance boost w/ 91, but mileage might be minimal. I like using 91 every onece in a while, but I'm so damn cheap I use 87 mostly.

Now...I notice a big DECREASE in mpg...at least 2 mpg drop when I use that cheap ass Walmart gas. It's a lot cheaper so I've tried it a few times...and every single time it sucks. I just thought it was a fluke at first.

Also, if you haven't put synth oil in yet...you'll get quite a mpg boost from that. I instantly went from 31/32 hwy to 34/35 w/ RPurple... and I've held that mileage consistantly for almost 2 years. I've even hit 36/37 before. In town mpg is still crap...like 26 or so.

And 75% of my miles I put on my car are on the hwy...180mi 1 way trips...so it's not a fluke.

 

Same here....

And it says recommended not required. The SC's require it but like I said up top I always use 91 no matter what.

 

93 octane only ever since it was new 8)

 

we dont get 93 here in winnipeg lol

 

the SC doesnt "require" it either.
its "recommended"

Stage 2 kit "requires" it.

either way, running 87 in a car tuned for 91 is not very good.

 

so what ur saying is putting 87 in my car over the winter is not good for it? what would be bad for it in terms of harming my car?

 

if you are lightfooted ALL the time with it, you can drive it on 87 without hurting it.
but i dont know many people who can do that.

basically the second you floor it on a 91 octane tune with 87 in the tank....its gonna knock,

 

yyeah...and god knows i am no lightfoot, i should go switch to premium next time i fill up

 

indeed. i used to run 94 but then they replaced it with 91, WTF, so i went to 93.

 

as for gas milage i say its all a mute point. i am getting near 30mpg daily driving on 89. but for power you can't beat a higher octane.

 

wow this is good info to know considering i just got my cobalt (FINALLY) it's awsome first car for me and i love it

 

i think husky does... im pretty sure the one down portage has 93 premium

 

The cars in its n/a form can run safely on 87 octane.

However, I know the car runs like a old mule.

I did notice (regardless of whoever said it earlier) when I went from 87 to 91(93) my fuel mileage went from a mere 28 to 33.

Now granted im turbo (and even before that) i put in a min of 91.

 

ill say it again...the same air/fuel ratio will be used, resulting in the same amount of fuel used as premium. You'll just yield more power, and less heat (no detonation)

 

the day i went to pick up my brand new ss, i asked my dealer if they put premium in it, cuz i noticed the gas tank was full. i know they were trying to do me a favor, but they filled it with regular, and the dealer insisted that if it took premium it would say it on the gas cap. i told him i have been researching the car for a year and i know engine knock will result from it. keep in mind its new years eve and the temp outside is barely at the freezing point. sure enough when i got on the road, my engine started crying. all i could do was watch the miles climb from 10 and apologize to my baby.

 

My sentiments exactly...

 

This descussion intreaged me enough to get out my cobalt bible (owner manual) and check for it's wisdom! It states...
" If your vehicle has the 2.4L L4 engine (VIN code B) or the 2.0L Supercharged engine (VIN code P), use premium unleaded gasoline with a posted octane rating of 91 or higher. You may also use regular unleaded gasoline rated at 87 octane or higher, but your vehicle's acceleration may be slightly reduced, and you may notice a slight audible knocking noise, commonly referred to as spark knock. If the octane is less than 87, you may notice a heavy knocking noise when you drive. If this occures, use a gasoline rated at 87 octane or higher as soon as possible. Otherwise, you might damage your engine. If you are using gasoline rated at 87 octane or higher and you hear heavy knocking, your engin needs service."
So my take is this, use 91 Not 87

This was word for word fom the manual! Just an FYI

 

you wouldnt be knocking even on a SC unless you were flooring it away, or driving heavily. I cant imagine you'd gun it off the lot knowing that they filled it with 87

 

for the most part...yes. but a lot of the bigger brand-name fuels, like BP, Shell, etc. actually do put cleaning additives in their premium fuel blends. not as much as you'd get out of a real dosing of bottled fuel additives...but it's definately in there.

i don't see me being with cheap on fuel with this car though...im so used to it costing about $100\tank for my truck that only last me 5-6 days anyhow, for regular, it'll be a relief to only pay like $40 for a tank that lasts me at least a week on premium. (ordering my new '08 Sport Friday afternoon)

 

VVT + almost 10.5 to 1 compression = it NEEDING the good stuff!!!

Also it TELLS you as much in your owners manual! Go slap the salesman in the forhead with your dick.

 

my car loves 94 from Sunoco....

 

Here in this part of va we only have 93 for the 90+. and It is great even better now that I got my tune lol

 

yah i was puttin in 87 for a looong time. and then my cobalt group told me why the **** are u doin tha? wanna **** yer car?? i put premium in and its been a better car ever since. also im proud to announce the Supercharger build will be underway within the next week

 

Only 93 grade premium has been pumped into my tank since I've owned my car.

That salesman was a *******. Even the manual states your only supposed to use premium.

 

yea my dumb ex put 87 on it one time cause thats all she could afford dumb broad i ******* hate her!!!!!!!!!!!!!!!!!!!!!!!!!!!!!