Hey, I own a 1997 pontiac bonnevielle se and i was just wondering wat kind of gas to use. In the manual it says to use the regular. But that is cheap and poor quality. I asked a mechanic and he said the higher the better, but i have also heard that the highest octane (super) or 93, would be too high. That the engine wont have enough power to compress the octain, and the deposit would be left in the cylinders or some place else. Can anyone explain how this works.

P.S.: its 3.8L series II with 205 hp and 240 torque, thanks.

Use whatever octane the owners manual specifies. Octane is very misunderstood with the public. The lower the octane, the faster, and more uncontrollably, the gas will burn. It is easier to produce, which is why it is cheaper at the pump. It is NOT of a lower quality. More expensive vehicles tend to require "premium" gas because they run higher compression, which will in turn create more power and torque. An engine with higher compression needs higher octane so it will not predetonate, which can destroy the engine. A higher octane means the fuel will burn more slowly and predictably. It will NOT create more power.

So basically, unless you are increasing the compression of your engine or increasing the boost on the supercharger, do not run higher octane than recommended in your owners manual. Higher octane will produce LESS power. By the same token, octane boost additives that you can find on store shelves will not increase power or mileage. They will hurt it. The only way they can increase mileage is if they incorporate an injector cleaner. By the way, running injector cleaner every oil change is the best way to keep your vehicle running smoothly and efficiently.

Hope this helps, let me know if you need further clarification.

Octane is very misunderstood with the public

Amen! I agree totally. If the owner's manual says regular unleaded, run regular unleaded. If it states premium, then run premium.

:iagree: 3800 n/a engines only need 87, the supercharged versions need 91+