after market diesel shops??????

[4Buck]

I have had up to 18.8 mpg pulling nothing on the interstate 80mph, I have had 21 or so pulling nothing on the hwy's 65-70mph

I get around that 10mpg when pulling my 34ft fifth wheel, 15 or so with the boat, and 8 with both.

might be better or worse as I am just going off the computer screen, not actual pen and paper, tank to mileage results.

Those numbers sound the same as my 2013 Duramax.

 

[eyexer]

in the oil patch the diesels don't get shut off all day. on frac sites they may run for days at a time. In Alaska in the winter they get shut off to do oil changes and that's about it unless they are stored inside. Some have issues from this some don't.