my dad had a 05 5.9 and for some dumb reason he traded it off for a new 6.7L. he was gettin 18 all the time and now he gets 16 empty and 10 with a trailer is there any way to get better milage out of it without ruining the warranties? it wouldn't be so bad if diesel wasn't $4 a gallon.

 

If it's a brand new Ram, the mpg's should come up as he breaks the engine in.