I find speed makes the most difference. With my 3.73 gears, 48RE and 12.50-35 tires, and Smarty Jr on sw2, I run at 1600 at 62mph, our legal speed limit. Hand calc'd unloaded summer around 19-20mpg us, winter 16-18. In sw1, it's 2mpg higher, both winter and summer. Truck's only been over 62 twice in its life. Probably never will be again. No need to go any faster.

 

dsl, until you change out the 4.10 gears and go to a 3.73 and take that heavy bumper off and put some good stock tires on, you really won't see better mileage. I won't argue over this and that. Just the simple facts buddy. I have a 05 3500 4x4 Dually 6spd and everything is stock pretty much and I am avg. 20mpg hand calculated.

 

Just for the heck of it I actually very easy on the throttle and was easy on the braking on trip from SW Fl to Tn recently. The crazy overhead gage said 26.8mpg but with pencil n paper it worked out to 24.7mpg. Coming home I said the heck with the great mileage and drove like normal (mostly interstate) and the mgp's dropped to 21.3mpg with pencil n paper, overhead still fibbing about 2mpg. We also have a Kia Sedona and it has never gotten this kind of mileage no matter how you drive it. Using Super Chips Tuner on Power setting. No Trailer but bed & back seat loaded pretty heavy.

 

542790 duralight filter. I put a duralite air filter that is made for a caterpillar deisel on my 2002 and increased my fuel millage by eight miles per gallon. Also jumped it up 4.5 mpg while towing. The air box comes right out and it attaches directly to the hose for the turbo.

 

Ummm....do you really expect folks to believe an air filter gave you 8mpg?

 

He hasn't said what his mileage is? Maybe his stock filter was so clogged he did gain 8 mpg. Now he gets 17 on the highway and 13.5 while towing thanks to the Duralite air filter.. :-)