I just bought a 05 f250 6.0 diesel. It has been lifted 6 inches and has 35 in tires. I am only getting 10.5 mpg. This is still after I got two injectors replaced and a performance chip put in. Some people tell me I should be getting a lot better while others tell me that is expected. any ideas or opinions? <?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o>
<o> </o>
Thanks

 

What speed? This engine should give you 15 mpg easy
Welcome to the forum. For engine specific question you might want to go to proper section.

 

Mostly highway miles. Mostly 55 to 65 mph
The truck had 88,000 miles on it.

 

At those speeds I am getting 14 mpg from my 10,000 lb flatbed.
The engine definitely needs checking. It is not V10 if you know what I mean

 

I've got an 03 with one of the real early 6.0's. It's got @160K miles on it.

Driving here around the mountains I get 14-15 mpg...on the interstate here in the mountains I get 15-16 and down in the flat land interstate I was getting 17-18 mpg. Mine is bone stock...I'd point part of the issue to the oversized tires.

Joe

 

Lift and big tires kill mileage. But yours is worse than I would have expected. However, these trucks do vary a lot from one to another. Also, have you corrected your speedometer? Are you hand calculating or using the computer display? Did you compare your mileage before the "performance chip"? Chips usually result in worse mileage. Simply because you enjoy that performance too much.

 

I get 17 to 19 mpg on Hwy and 14 to 15 on side roads. Not too bad.