Ever since I can remember I have used 93 octane on my 3.8 camaro. A while ago I changed the intake and valve cover gaskets on my motor. After I got it all together I noticed I had a service engine soon light and figured it was because of a rocky start up after it sitting too long and the repair I had made.Tthis last weekend I went to fill up and all the 93 pumps were being used and I did not want to wait, so I put the cheap gas in it 87 octane. After about maybe two or three blocks of driving the SES light went off and a hesitation under light load from take off was gone. My ? is, can high octane hurt your car if it is not made for it or is there something wrong with my car, maybe lossing compresion and can no longer burn high octane fuel, since lower octane is more flamable.

 

you dont need anything higher than 87 octane in the 3.8.

 

I'm curious, what is the difference between now and when I got the car new?
I never got the SES light or the hesitation until now and I had always used 93.

 

But le manual says 89

 

The octane that you need is going to be based on the altitude that you live at. Whatever the regular gasoline rating is for your area is going to be fine for your car. Putting in a higher octane gasoline isn't going to damage anything, but it's going to cost you more and not get you much, if any benefit. Often times if you put in a higher grade gasoline you'll see an increase in fuel economy because the car is going to push the spark advance farther, but it usually doesn't offset the cost of the higher grade fuel.

 

1) You need to re-trace your steps and see if maybe you missed something such as a sensor connection, etc.
2) If your engine doesn't require high octane, the only thing you'll be hurting is your wallet.
3) You got that backwards. Higher octane fuel doesn't need a high compression engine to burn it. But a high compression engine needs higher octane to run correctly. If an engine only requires 87 octane, you can run any octane fuel you want, but anything above 87 would be a waste of money.

 

if it says to use 87 then anything over that can just be a waste... I've heard cases where the higher octane leaves a residue or something and can damage spark plugs (but i think this is more the case with octane boosters)