is the premium gasoline like shell v-power really worth its price? wat does it do for the engine. i drive a 2001 is300 with 67000 miles on it should i pump premium?
Just advertisement, remember, oil comes from the same place but they do add some things to it
premium grade gasoline is usually a higher octane.
What does this mean? It means it burns slower.
Why woudl you want that? if your car has higher compression pistons, the heat from the compression stroke can actually cause the fuel mixture to ignite early causing detonation (see the diesel thread for how diesel engines run on that instead of spark). Detonation (which is technically called pre-ignition) can harm your engine by causing the pistons to be forced back against the revoluton of the crank. AND since it's hotter, it can cause teh tops of the pistons to melt.
To combat this, higher octane fuel burns slower, so that it is less prone to pre-ignition at elevated temparatures. This makes it necessary for cars that run higher compresion, or forced induction.
If you use premium fuel in an engine that doesn't need premium fuel, there's a good chance that the fuel won't burn completely on the power stroke, causing greater pollution (or at least causing the catalytic converter to clog early), and worse fuel mileage.
Read the owners manual and see what octane it recommends for your car.
Most owners manual say some thing like use gasoline with at least 89 octane. I drive a civic and I was running the middle grade and I could tell a difference, but now that the cheap stuff went up like 25 cents a gallon, I'm using the cheaper stuff again.