Why does the manuel say only touse # 87? will I really mess up my stand if I use 89 or 91?

 

No, you will just waste your money. You won't get any gains unless you are running a tune.

 

no... if its hot you'll avoid detonation issues and may get a bit better performance... otherwise no difference.

 

+1

 

...Because that's what you're supposed to use..

 

+1 Arwing.. lol.

 

Use the 87 Octane that is all that is needed unless you have a tune for it. Also using a higher octane fuel than the car is programmed to use can cause excessive carbon buildup within the combustion chamber. Since the higher octane fuels burn slower and the timing is not advanced to handle the slower burn it leave unburned fuel in the combustion chamber which can lead to detonation.

Certain high performance engines benefit from use of high octane fuel. For other engines, using a fuel with a higher octane rating than the vehicle requires sends unburned fuel into the emissions system and catalytic converter. This puts unecessary stress on the emissions system. For some vehicles, a rotten egg smell coming from the tailpipe signals use of too-high octane gas.
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Richard