Wow, I just got 16mpg with my 1999 4wd Ford extended cab 5.4L engine. Thats up from 10-11 mpg that I was getting this winter. I wonder if the warm temperatures helped me acheive this or if they started making the summer formula for the gasoline. I also switched to Amsoil synthetic motor oil from the Mobil 1 synthetic a few hundred miles ago. Maybe that has helped. The Amsoil does not seem to be leaking from the engine like the Mobil 1 syntetic did. I will keep an eye on the dipstick and see if this still holds true after a few thousand miles.

 

U driving it any differently? I noticed huge differences in MPG on my truck just depending on how I'm driving. When I was breaking in gears on my truck I was getting 16mpg... then I started driving it really hard and got 13mpg... then once I was use to the new power I went back up and started getting 14.5s since I wasn't on the gas as hard as usual.

 

I might have been a little more gentle with the gas on this last tank but lets talk about last summer when I drove the same route with the air-conditioner on and driving very aggressive with lots of WOT. I was getting 15.x mpg then.

It just gets me how I get 10-11 mpg in the winter and 15.x mpg in the summer. Its not even summer yet and I wonder if I can expect even better mpg when the temperatures get even warmer along with switching all the fluids in the truck over to Amsoil...

 

You normally notice differences in the winter. I had a thread in here somewhere about it.

Basically no one knows for sure what it is, but the winter gas, denser air, and some other factors play a hand.

I get about 14.5 if I'm light on the gas. Usually got 12 in the winter.

 

You normally notice differences in the winter. I had a thread in here somewhere about it.

Basically no one knows for sure what it is, but the winter gas, denser air, and some other factors play a hand.

I get about 14.5 if I'm light on the gas. Usually got 12 in the winter.