I've got to get my Webasto in this truck. I took it out my IH before I sold it but haven't had time. Well, I'm now freezing my azz off.

Your mpg seems good to me. Even with a empty box, my 05 IH w/ACERT only got 6.5mpg on a good day. I hated it

 

Check your turbo system for leaks: charge air cooler; air-to-air hoses (especially where clamps are); exhaust manifold etc.. Lose your ACERT muffler. Last but not least: do a Dyno on the CAT. It'll be worth every cent you pay for it.

 

I sold the truck a few months ago, so I'm not worried about it. I now have 1998 engine and dont worry about my mpg seeing I'm getting close to 9 out of it overall LOL

 

So you got 8.5 MPG. My '06 Volvo w/ 465 HP Volvo D12 routinely gets 9.0 MPG when I'm MT. And that it with a heavier box trailer. If I had your trailer, I could get 9.5-10.0 MPG.

 

thats damn good.. but my company truck has a 515 detroit.. 10 speed 3.58 gears.. runs 66 and i'm a bit rough on it with alot of stop and go..almost like clock work.. 7.5mpg.. when it was turned up to 76mph it went down to about 6.8.. oh yeah and it pulls like an animal. i talked to my buddy yesterday that has a 6nz 550hp, 18dblod, 3.36 gears in a 379, he runs between 6.5 and 71 and he's averaging 6.1..

by the way to the people that i said them long nose trucks cant get ok milage.. i was wrong. :lol:

 

Have you ever counted the gallons of fuel purchased in US gallons versus miles driven?

 

I doubt it..And that's in my opinion is the only fair way to count. What you have paid for, not what some dashboard display said. And the more miles is the better. Most important is your average!

 

But also, if you go by the PUMP, you could be between 3-10gallons off too. Just last week I filled my tanks to the bottom of their filler-neck, then for the heck of it I added 6 gallons, it was still at the same spot on the neck. I'm just saying. 6 gallons on each tank made me loose 1mpg....... **** it too hard to judge. the dashboard display actually accounts for HOW MUCH FUEL passes thru the injectors which gives you a BETTER reading.

I honestly don't trust either method and just know I make WAAAYYY more than I spend, so I am happy LOL

 

I know. That's why i've said the more miles you run, the better your estimate will be. I also fill it up at a very few familiar locations, so the angle my truck and tanks stay, is always the same.