6.7 diesel from good to bad fuel mileage
I have a 6.7 in my 2008 ram 2500, I used to get 20/22 mpg hwy mileage.It's got approx. 47000 miles the fuel mileage has dropped from 20/22 mpg hwy. to 13/15 mpg. No significant problems runs good no modifications cannot figure out. Speed does not matter, 55 mph or 70mph still poor mileage. Any suggestions.