If you always fill the tanks, or only calculate from fill-up to fill-up, then the gallons burned are the same as the gallons you bought. Unless you're running heavy and need to cut weight any way you can, I've never understood the logic behind NOT topping off the tank whenever you've stopped for fuel. Time is money, and it's a waste of both making extra stops to buy a little here and a little there, especially when half the time you might end up behind the jackwad that's taking his 30. Just fill the tanks and be done with it.
I don't know why (no engineering affirmation so far) but I always heard that ISX was best to stay between 1400-1600 rpms but since I I got the scanguage I see that it does not matter too much for the oil pressure. Maybe there are other reasons to keep it at higher rpms . I don't know about this staff but I heard it from more than one mechanic.
That gets closer to maximum horsepower. Every engine plate, like on my own Cummins ISX lists the maximum horsepower rating at 2000 rpm's. I don't think many drivers get that high in rpm's! I have on occasion, but in very technical situations with steep off road. Normally I do run between 1400 and 1600 rpm's on the big road. I'm not as concerned about mpg as many O/O's are, but the engine just feels better in that band of power train if I am applying any kind of throttle.
I have 300gal my trk weighs 23500 empty bobtail. I gotta watch how much i fuel or i cant book a load because im to heavy. I suggest if you use calculator method like in my case pick a fuel level on the gauge like 1/2 and calculate each time . Youll be close. I trip my fuel each load i know how much fuel i burn based on weight and route. Then i negociate with a broker to max my profit per load. Trust me i get bored always tryg to find a way to save a buck
