fuel mileage

I see you have been a trucker for 20 years so I suspect its safe to assume you have better results than this.
So many times I think drivers should say "Im getting" and then go on to the equipment.
Give a bit of info on the truck , routs , loads and maintenance history and you should get some responses.

 

what year of n-14 . , a lot of variables . The present fuel type should be ok. check your tandem alignment trailer tandems. Go to the point that engines are load based in fuel delivery. Even internal friction of engine and drive train also affect , brakes dragging, and go down the list. Most fuel consumption is starting and climbing . On the engine side injectors not metering correctly. , fuel knock excessive black smoke hard starting usually an indicator of a fuel system problem.