i have a 2006 cobalt ls, and i use the 87 octane, will useing the 89 or even the 93 make my car run better, or give me better gas milage?

 

better gas mileage no..... higher hp possibly.... maybe a few more hp but for an LS not worth the extra 20 cents per if you ask me

 

I've heard you might actually get a slight drop in MPG with higher than needed octane, but you might pick up a hp or two. Once in a while I run 89 octane rather than 87, I don't bother with premium (too expensive.) I feel a slight gain in power, not really noticeable.

 

h slight gain you feel could also be in ur head right? U might THINK ur going faster when u are probly going the same.

i have had countless ppl tell me that you can lose power from going a higher octane than needed. Only need high octane for high compression engines or engines with forced induction.

 

you're wasting your money using higher octane... it is no helping you out, if anything it's hurting... all octane is is the temperature at which it burns... using higher octane means it's harder to ignite, which will most likely slow things down if your engine is not meant for it...

 

For your car mid-grade fuel would be the best. 91+ is probly not good to use cause your car's not meant to run on it. 89 is a mixture of regular and premium and you would see the car running better and maybe slight increase in performance.

 

no, it won't gain power on stock tune and especially on a stock build. stick with the lowest octane you can get away with that won't have the engine knocking (typically 87). if you could alter your ignition and fuel to take advantage of 91-93 it might net a few hp, but nothing drastic that you would notice.

the higher the octane level, the slower the burn, and in turn the more resistance to detonation. it's not harder to ignite at all.

stick with 87 unless you're running nitrous or some other sort of forced induction, then you want 91-93 if that's what you're tuned for.

 

This is a common misconception. Octane rating has nothing to do with the fuels ability to make your engine produce more power. It is the stability rating of the fuel. The misconception comes from the fact that fast cars usually have higher compression engines which require the more stable gas. So people equate high octane to high speed. You want to run the lowest octane you can that doesn't effect performance. Anything higher is just a waste of money.

The SS and all newer high performance cars can actually tell what kind of gas you have. They will adjust your car's power to use the type of gas you are running. If you put 87 in an SS, it will run a lower power level to insure no problems. It even says it in the owners manual.

 

^^^ Bingo.

I knew a guy who ran 115 in his cutlass back in the day because he thought it was faster lol

Most factory turbo or supercharged cars can run lower octane, they just will pull a bunch more timing typically to warrant against the knock.

 

well said halfcent

just use what it says in your owners manual

 

wow, i didnt think i would get this big of a response, lol thanks alot i was just wondering, i donno if the 20 cents is worth it anyway esp if i dont need it lol

 

i ws running premium in mine just cause a higher octane is better but now with gas prices up ive moved down to mid grade and i think it runs better on mid grade than on the premium

 

this may not be the most appropriate response, but I get my ss/sc on friday, i also own a 2003 silverado ss, and have upgraded pcm, corsa sport and a tonneau cover for aerodynamic reasons.
my truck 6.0 l is 10.0 to 1 comp aluminum head. 91 octane minimum.
96 liters of fuel could take me 300 km in town.

i started adding 1 container stp octane boost for in town driving, and instantly got up to 450 kms per tank.

i add 2 on the highway, and can get up to 750 km per tank. 550 max, without octane.
ive never noticed any power difference, however, i believe the octane allows pcm to crank the timing on low torque situations to achieve fantastic mileage. i buy caseloads of octane and have documented the fuel savings which (after octane cost of $4 / tin), saves 15-25% mileage in any driving condition, including driving thru the rocky mountains at 85 mph.

believe it....or not!

 

higher octane gas gives you no hp no better milage it gives you nothing all it is for is if you have a high performance engine like the ss/sc that tend to run a little hotter that normal that is what higher octane is for to keep the engine from pinging or knocking

 

simple answer... no benefits for premium on the 2.2...

 

i find that sunoco has the best gas

 

Octane is a rating of a fuel's ignition point (as in temperature at which it burns). The higher the rating, the higher the ignition point of the fuel.

If you put 87 octane in a Cobalt SS/Supercharged, for example; there is a high possibility for preignition or spark knock/misfire because the higher compression in the engine heats up the 87 octane to its ignition point before the piston reaches TDC (Top Dead Center) and therefore prematurely ignites causing spark knock/misfire.

If you run 93 octane in a Cobalt 2.2L, the 93 octane will not ignite when the engine is at TDC. Instead, it will ignite too late due to the lower compression in the engine than the 2.0L Supercharged, and therefore will not build up enough heat to ignite the fuel as efficiently as if 87 octane were used. With the 93 octane in a low compression engine such as the 2.2L, the fuel may even ignite after TDC which would actually rob you of power due to the fact that you are not able to use the full stroke of the piston to create power. This is also considered a misfire.

In both of these cases, the PCM/ECM will receive a message from the knock sensor telling it that there is a misfire in the engine. The PCM/ECM will then adjust the timing (spark and fuel) accordingly to effectively get rid of the misfire, the PCM/ECM will then start to slowly adjust the timing back to where it was before the misfire and when it starts to get the misfire again, it will adjust to get rid of it and repeat this several times until it eventually learns a timing setting that is most efficient without getting a misfire. But the engine will not be running as efficiently or with as much power as if it were run on its reccommended fuel. The PCM/ECM does not have unlimited adjustment on the timing of the engine, it will eventually run out of adjustment and you will be stuck with a misfire and a CEL/MIL.

In short, always run the recommended fuel unless you have modified the engine with forced induction or raised the compression of the engine.

 

87-89 octane gas are the ones to use, 91-93 are a waste and as stated above, can cause power loss.

 

This is right out of a gm TSB

• Use the Recommended Grade (Octane) Fuel

Purchasing higher than required octane fuel is a waste of money. Using higher octane fuels in a vehicle that only required regular unleaded fuel will neither increase performance nor improve gas mileage. In all cases refer to your owners manual and ONLY use the octane rated fuel recommended for your vehicle.


Important: In high performance GM vehicles that DO require Premium (91 octane or higher) fuel, you MUST use fuels of at least this octane. Use of lower octane fuel may result in reduced performance, knocking, and/or permanent engine damage not covered under the terms of the New Vehicle Warranty.

 

You always post such smart posts . I think your up there with brian!! Only without* the sarcasm and comments :P (Hides)

 

so, do you have to run high octane with the cobalt ss/sc??? what do most of you run? i really wouldn't want it if i'm spending four bucks a gallon no matter what at the pump.

 

I Just got a ss/sc yesterday. What octane fuel should i run in it.

 

Nitrous oxide is the gas that increases performance

 

If you read the thread, you will easily find the answer to your questions. Yes, the SC uses high octane. You can run low octane, but your engine will reduce its power to avoid knock.