What to look for?
#2
#3
loose front end parts is one of the main problems, chack all ball joints, have someone turn the steering back and forth with the engine running and get a good look at them all, other than that the 5.9 will net a lot better fuel milage than the 6.7 which is 07.5 and newer
#4
wow, if your only getting 13mpg's you either have a problem somewhere or you drive it hard, never heard of one that low, and if he is getting 18 pulling a trailer, thats awsome, but i have always averaged 12-14 with a trailer, and 15-17 empty with any 6.7 i have drove, and always around 17 at the very worst with a 5.9 and alot of the time, have them up in the 20's
#5
In day to day driving.....
12 - 13 is normal on 6.7
15 - 17 is normal on a 5.9
Only way that the 6.7 is seeing those kind of numbers is if the DPF and EGR are gone and it's tuned.
18 MPG while towing......I think he's been looking at the lie-o-meter too much.
On mine, making the power it does, I get 16 - 18 in day to day, 20 - 21.5 cruising at 70 - 72 unloaded.
Last edited by Coal Train; 04-27-2010 at 06:32 PM.