Charge air cooler would be my #1 thought. Do a pressure test or just look for a hair line crack. Run some 300° silicone along the crack for a quick fix until you get another one
Currently hauling 43k so I'm grossed at 76120. I never idle(apu) very little city driving. I use cruise religiously. I'm on 81n in Virginia so I got some hills
if they ran the overhead a little tight it would lose a little mpg. on a 60 series takes a little time for the overhead to loosen up. plus their is a lot of things that factor mpg. one of the main reason rite know could be blended fuel, along with high idle time.
Read this: http://www.thetruckersreport.com/tr...56-extend-it-fuel-lubricants.html#post3047809 It will solve your problems
That's how my truck is 4.8-5.2 I did 5.9 today running 400 miles today with a empty trailer new record for me did 3.9 two weeks ago on I-10 heading for AZ grossing 62,000lbs
Well when I run the trk at 70+ mph, I usually see my mpg's fall into the 5's. When I do what I normally do, run about 60 mph, day in and day out, I see high 6's or 7's loaded, and 8's usually when DH or empty. Are you running your trucks hard and fast? I am not bragging or anything, but I am the one you pass and I am sure complain about driving so slow. I am sorry if I made you mad, but getting to a trk stop 30 -45 mins later than you do, doesn't mean that much to me.
