At 850 miles I hooked up to the backhoe, I couldnt wait, and pulled it to Pheonix, AZ. 250 miles one way. I got 9 mpg on the way there and 12. 8 on the way home. The trailer and tractor together weigh just under 24,000 lbs. I am now at 18. 6 mpg running around empty. 2300 miles on the truck. Just hook something heavy to it and pull. I would wait for at least the 500 miles the book suggests. Then act stupid and enjoy.