I know it been asked before but
So Ive had my car for almost 3 weeks now and the dealer told me that putting in regular would be fine but I got my owners manual today and it said I should be putting in 91 is whatever is closest to it.

MY question is what octane should I be putting in my car? as of right now im getting 500km per tank that is a mix of city and highway driving.

you have a 2.4 you should be fine with regular. as long as its not shit gas.

I normally put chevron gas or petro Canada gas in the car.

"Premium recommended but not required"

It has been proven on this forum that you'll actually get better mileage and performance with premium gas, and that it's better for your engine, but at the end of the day the bold text is what's in your owner's manual, so do with it what you will.

you can run regular, but performance may suffer. I'm not too familiar with the specifics, but your car will adjust to the lower grade, hence lowering performance.

Just put 91 in.

performance does suffer with regular go for the premium gas better performance and mileage trust me i got the same car 07 SS Sedan

the 2.4 will run on anything i once had to run mine on 87 octane just be aware and listen to your engine for knocks if it knock put the highest octane you can find in immediately

2.4 has VVT (Variable Valve Timing)

Proof:

Cobalt 2.4: 173 hp with premium gas
Upcoming G6 coupe, same 2.4: 164 hp with regular gas

Differing tunes as well. But again, at the end of the day, GM wouldn't say "NOT REQUIRED" if regular gas did any actual harm to the engine. Just put 91 in though... only costs a few cents more.

damn and I just filled my tank.....................look like im going to go do some driving tomorrow and the fill it up with premium.

thanks for the info.

91 at least, hell i run 93 in mine, your car wont perform nearly as well and will probably knock with lower octane gas

91 at least, hell i run 93 in mine, your car wont perform nearly as well and will probably knock with lower octane gas

You have a notably modded SC. 87 isn't as bad for the 2.4.

i had 87 in my 2.4 but it ran smoother and performed better with premium. I always put premium in it, gets better gas mileage and is overal, better for the motor

Yeah Chevy told me that higher than base Octane isn't the best choice for my 2.2, but the cav 2.2 I had ran fine with mid grade...never got premium, cuz I heard it would mess up the motor.

91 at least, hell i run 93 in mine, your car wont perform nearly as well and will probably knock with lower octane gas

Altitude plays a factor whether you have 93 or 91 octane. I'm at 4500' and I don't have 93 octane as an option anywhere.

Yeah Chevy told me that higher than base Octane isn't the best choice for my 2.2, but the cav 2.2 I had ran fine with mid grade...never got premium, cuz I heard it would mess up the motor.

yea the 2.2 was designed for base octane ..... the 2.4 that has vvt will run on any but at 87 it runs rough and the power is turned down but with 93 it runs smooth with all the power

the 2.0 sc or tc i think the manual says 93 recommended but not required but i think their have been people on here that have had problems from running anything less than 91

i run 93 now but i have ran 87 before and its a noticable difference in performance...to me anyway.

now that's its' gotten cold, my idle is all screwed up(2.2). I've run gas line antifreeze to clean up any water in the lines, but still rough idle. I've been running 87 all along, I think next time I'll try 93 and see what happens.