do not buy detroit 14 liter it sucks!!!!!

What's ur weight?

 

You should be getting better than 5.75 running mt. I ran am mt ashley furniture trailer from virginia to wisconsin and I was getting 8 mpg. I get 5.83 if I'm hauling a heavy load 40K+

 

Does your engine sputter once in a while and release some black smoke? I was getting low 5s and high 4s few months ago because I had a crack in my air to air, mpg went up since I replace the air to air.

I have a columbia and they suck, I saw a lot of younger guys with them so I thought they were more reliable, in the last 6 months I replace everything around the motor now I have an oil leak, everything around the motor stop breaking now everything inside the truck breaking. I am ready to get a hood

 

How does it feel? Does it hesitate, is it weak climbing hills? Or, does it feel strong and have a good throttle response? Does the engine have any strange quirks? (Hard to start, unusual noises, stalling, bucking?)

 

Wish I could get 5.7mpg all I get is 5 out of mine

 

I ran an 04' with a 10spd Ultrashift a couple years ago. The truck was former Trans Am and Spec'd with 3:58 rears and the 14L. I ran 65 mph with 25K and got 6.7. I got 7.2 running 60 with 25K. This was running reefer too. Full out at 75 we got 5.75 with 45K in the box. My old boss told me he runs 67 and gets 6.5 after a recent rebuild.

KH