The Stovebolt Site Forums The Shop Area General Truck Talk 7.8 miles/gallon, sound right?

That does seem like terrible mileage. My '89 K3500 with a 454 and 4.11 gears does better than that most of the time. But with a heavily loaded trailer it sometimes does worse.

My GMC Suburban with a 270, sm420 and 3.08 gears seems to do more like 14 mpg. I would not expect to get 20 or more, but you sure should be able to get better than 10 mpg...