Is it ok if I use mid grade gas in my 04?

 

I have an 05 with the 5.4 and personal experience, mine runs worse on mid grade than it does on regular! These trucks are wierd.....with mid grade it does that "dieseling" crap at idle even worse than normal. (the dieseling is why I will be getting RID of it as soon as I get it paid down enough as I don't have thousands to spend on this thing for cam phasers ect.)

 

You can put anything at the pump in it, except diesel or kerosene.

 

lol.....yes, just because it sounds like a diesel doesn't mean it will run on diesel!

 

There is no performance gain to be had by running higher octane fuel on a motor not designed/build/tuned for it.

However, if you where to have a tune, bump your timing, raise your compression, add boost, there would be a benefit, however with a stock motor, it is a waste of money.

 

I think it depends on the region too, I run mid because in MT mid is 88 and regular is 85 and the truck is designed for 87, But I grew up in So Cal were mid is 89 and regular is 87