Hey well like i said early i just got an 03 mustang gt.
did not have to fill it till about now.
at the dealership they did not tell me what kinda of gas to put into the car.
please help i was thinking preamium??

what gas you put in car.

 

you don't need premium unless your car is tuned for it. a stock mustang is tuned for plain ole 87

 

yep regular gas

 

Ok thanks a lot for clearing that up for me

 

i use 87 when i will be on the freeway at night, or when there is little traffic. when driving in bumper to bumper traffic the car will get hotter and knock a little, not enough to do damage but just enough to embarass you. so i use 91 when i am in bumper to bumper traffic

 

i have never heard of that happening. unless it is an older car that is on its way out, you should put what ever your car is meant to take (so if the manual says 87 octane...then put 87 octane in) if you put 93 octane in a car that takes 87, your not helping the car in any way. The octane levels determine how easy it is for the engine to combust the gas.

i put 93 in cause my car is tuned for 93. i also have a 100 octane tune that i never use cause i cant find 100 octane around where i am at lol

 

ok so i am started to put regular in my tank so i m going stay with it.

 

actually octane is the measure of a fuels resistance to burn....thus if you are running higher compression you need to run higher octane combat pre-ignition(knock). there are other aspects that can lead to knock...one of them is raised intake temp. like driving in bumper to bumper traffic on a 100 degree day....this can raise the temp of the intake air to 125+ or more. this can lead to low rpm knock, regardless of what you have previously tuned for.....

 

Happened to me 2 summers ago (I HATE rubber-neckers). Heat, whether it be from the air coming in or engine itself causes knock. In addition, heavy load conditions do the same thing. My dad's old F150 called for 87 but he always threw in 89 since w/ a load in the bed, 89 kept the engine happy.