Cheap diesel, bad mpg's?

Northbound where? How heavy were you? What cetane is in that wally fuel? Get yourself some quality fuel. Spend a dime for it. If you are fighting mountains that are 15% up and OMG down that will translate into fuel gallons per hour burned.

There is no such thing as cheap fuel. The last time I tried cheap fuel was 1.30 in Jersey when we were experiencing our first National Crisis at 1.99 fuel in those days. Trucks came and drained that old man's 3000 gallon tank by dinner time leaving him to wait until after midnight to purchase more fuel at a loss close to 2.00.

To me fuel is life. Fill at half tank and keep going. Good luck!

 

I'm from the north east and a few years back there were some Hess stations (not all) in Pennsylvania that were 10 cents cheaper per gallon then the others. I filled up there every once in a while but, like you, I noticed fuel mileage drop almost a whole gallon per mile. It turns out their fuel was 10% biofuel so, I stayed away from it.

I too keep meticulous fuel mileage records by hand. Mostly as a preventative maintenance step. If the fuel mileage starts tanking it is an indication that something is wrong. If I haven't taken any measures to increase mileage and it starts to increase it lets me know to start finding out why.

I get 6.6 to 7.1 (mostly 6.8 in a 97 Peterbilt 379, 550 Cat, 13 spd, 3.70 rear end ratio and 24.5 tires and I'm pretty proud of that. I have had on occasion been dragged down to 5.9 with tall or OD loads and also get a consistent 8.1 empty (I've been paid to drive empty from L.I. to OKC.)

I have read that some fuel might not pack as much energy during combustion that others. Can't remember if it was related to cetane or something else.

 

Not necessarily, I could never get any better than 6mpg through Nebraska on I-80 either way. I ended up chalking that up to the road condition. Back in 07-08 the road was very bumpy almost like washboard, kind of like I-20 in the south east

 

Don't get the off the wall diesel. I only ever get at the major's. Petro, TA, J, Pilot, Loves. You need the additives they put in their fuel as well. You will roast your fuel pump using cheap diesel amongst all kinds of other issues you will develop.
I don't know the scientific reason, but i'm sure your MPG suffers as well.

 

Nebraska vs the wind. Kansas versus the upgrade all the way to Denver. Get pretty #### high over a few hours from say Kansas City.

Ive always purchased Petro or Pilot fuel. All others where necessary with TA or 76 particular favorites. I think there was only one fuel pump failure over the few dozen rigs Ive run and that one has a story behind that I might share here someday. There was a engine I turned over once but it's not the fuel problem.

Texas to me is not too bad. I don't recall figures for mileage but expected anywhere from 4 to 6 most of the time there. We were more concerned with keeping 300 gallons on the truck at all times, fueling daily (That worked out to almost 80,000 dollars fuel per year)

One rig I exclude from fuel mileage is a GMC Astro suicide cabover with it's big ### ear killing turbocharger that screamed. Im deaf and dispatch discovered that I could stand it when others ran screaming about ice pick problem in ear. To this day I wonder about that turbo. It was a most excellent shift indicator and on the other hand a whirling dervish I wanted OFF that rig. Had a fire bottle on the doghouse the whole time.. scared of it. It drank fuel by the tank. Wouldnt pull a hill and laid down on traffic lights of which there were many.