ok i drive a lancer es 03, my question to you guys is: what kind of gas should i use? i currently use premium, but a friend of mine said that it doesnt matter and that im just wasting money. is there a difference in mileage depending on the octane?

 

If the car says it takes premium dont use anything else...

And your friend... is a dumbass

 

Your probably fine not using premium since your car isn't turbo or running at higher pressures. The higher octane keeps the gas from exploding from just sheer pressure which can happen in cars that are turbo or just running high compression rates. Truthfully I don't have a turbo car but I use higher octane and the only thing i have done is full exhaust, cold air intake, and egr block off. I find I get better gas millage though with the higher octane.

 

wow stupid question what is egr block off

 

never mind just read a sticky