I wouldn't complain if you're getting 18 to 22 empty. I have two buddies who just bought 08' 6.7's and the best they're doing is 12 to 13 mt. If you're doing that good loaded I'd say that wasda%& good. I run 19 to 20 in my 02' 5.9 mt and 12 to 14 pulling my horse trailer. Loaded with 4 horses and gear it's approz. 11K. Trucks chipped,aired,fueled and piped. Personally I think your doin great. And itshould get a little better, assuming you haven't really got it broke in yet. That takes about 30,000.

 

don't get me wrong, the 18 - 22 i love. it's when i get 10 - 11mpg with 4k behind me that is kind of disapointing. my 98 gmc 2500 with 120000 miles got 8mpg with the same trailer, hardly justifies a $53000 sticker

 

well beasty tip the scale at 9800lbs,im carring this weight everyday and i still get 15mpg whit about that 4klbs over ur truck so i think you should do better than me by a couple mpg....
if i put my 24' flat behind whit 8K total weight maybe i go down to 12-13 mpg but no less, not much difference towing or not for me...
i got 35' tires so its must be harder to pull but engine turn slower so i guess its negating the pull effect....

 

I just looked up in the TSB section of Dodge Forum and there is menion of at least two spereate TSB's regarding soot accumulation from DPF regen malfunctions, although they do not say how to tell one way or another. If Parts/Service gets ahold of this thread he may be able to shed more ligh ton this issue.

 

Damn...My '07 2500 5.9 w/4.10(bone stock)with only 5k on it is getting14-15 mpg towing 8500lbs at 75mph, but only gets 16 or so empty. The empty mileage is SoCal traffic though.

 

If you are actually doing that well empty (read hand calculating your MPG) then you are doing better than most have reported here for a 6.7. As far a towing mileage I used to tow a 4000 lb 24 ft camper with my '99 powerstroke. I got 10 - 11 mpg pulling it. I upgraded to a 9000 lb 28 foot camper and got 9- 10 pulling it with the same truck. I upgraded (kinda) to an '04 powerjoke and got about the same pulling the heavier camper. I now pull that same camper with my '06 5.9 and get from 9.5 - 11.5 pulling it. I am pretty sure that wind resistance plays more into the equasion than weight. Enclosed trailers have a flat back that creates turbulence and a sucktion behind them that robs fuel economy. I used to have a high top cap for my Ford trucks with a very flat back, it used to cause my mileage to drop when I had it on the truck. If you look at air planes or submarines they have a tapered back that reduces the problem and increases their efficiency. It sounds to me like you are doing pretty good and just have your expectations a little too high. Going from 8 mpgto 10 mpg towing is a 25% increase in mileage and a gasser won't get near the empty mileage a diesel will. Plus your diesel will tow that and a whole lot more for 200k - 300k miles and love it, the gasser would never get that kind of longevity while towing regularly.

 

Another thought. DO you have the 3.73 rear end or the 4.10's??

That will make a huge differance

 

i have the 3.73's

 

There's your mileage loss right there. Although you have a ton of power in there your rig is geared for Highway cruizin, not neccesarily towing. I have the 4.10's a taller towing gear. You have options yet though, dasnake regeared, he is happy with that, additional overdrive or added power chip/programmer

 

Just my .02 but I went on a hunting trip this last fall and I have an 06 Mega with a 5.9 my cousin has a 96 with a 5.9. The truck we took was my cousins boss new 07 6.7, pulling a trailer on a 700 mile trip one way, out and back his truck was getting about 10mpg. 3.73 gears and 10,000 miles, we figured the trailer was about 6K lbs.My cousin and I were floored by this hand calculation. Needless to say we gave him a little extra ribbing about this, as well as a little more fuel money then we figured.Maybe it will get better in time.