I disagree, if something is making the vehicle perform badly.. then it is required. He could put water in the car if he wanted, nobody is making him put a certain Octane blend in the vehicle. That being said in the manual it says "USE" 91+ and then it says "May also" it is just being vague. If you are saying "The cobalt will move on 90< octane" well you are correct, but is it worth risking your engine to save a few bucks? If so.. sell your car and get an economy car.

The knock sensor should not adjust actually, the amount of air compression will eventually cause the engine to spark prematurely. It wouldn't make sense if this dude ran 87-89 and the knock sensor adjusted to higher heptane reading and lower compression, it doesn't work that way unless your sensor needs replacing or GM rushed that part of the car, the KS should always stay linear to a certain air compression ratio.

 

Wish I could remember the thread. Pretty much the 2.4 can run on 87 or 91+ but a few members had issues on 89. From how they described what happens it sounds like the computer cant quite figure out 89. And that causes issues. So I tell 2.4 guys to run premium or if they dont have access to it then just to run 87. The car can run 87 but doesnt run nearly as well and on my car at least I do notice a 2-3mpg drop during the same loop of driving. (compared 4 tanks of 87 during similar weather)

 

So can I just switch to premium or what?

 

You should be on Premium, period.

Unless you aren't in an SS.

 

2.0/2.4 Recommended premium by the owners manual.
2.2 run 87


So just switch to premium

 

93 in my 2.4.

 

Yeah I'm a 2.4 SS, I'm just asking if I can just start using premium...like is **** going to get messed up if there is other gas in the tank?

 

^^thanks for the info man

 

No problem. Ive switched a few times (during a short road trip the station only had 87 and 89). And once when I switched back to see what the con was of running 87. Im currently back on 93.

 

Give it a tank or two to really notice a difference, it's not going to be like a night and day difference right away, but you'll definitely be happier with the car running premium.

 

No it won't hurt anything. Just fill up with the correct gas and you are good to go.

 

93... it still has midrange knock on 93 and i'd run the "95" we had if they still offered it... found out it was really 100 octane and oxygenated lol.

 

Step 1 - Read the manual
Step 2 - Do what it says and you won't have knock
Step 3 - /thread

 

Sunoco 94

Absolutely LOVE butting into "OMG it costed me X amount to fill up today" conversations, which are typically expressed by those topping up with 87 octane on engines that sip gas even when hammered.

 

Sunoco Ultra 93 (Daily Driving)

Sunoco 260GT100/CAM2 (for fun), Yes I'm tuned for it

 

i run 12 octane. yup, 12.

 

87 in my care. runs fine. sometimes ill splurge on 89

 

100.

 

Did you not read above? for 2.4s its recommended to be on premium and 89 isnt a good idea. Not trying to be a dick here but it is recommended and they do run a lot better on 91+.