Quote:
Originally Posted by tweety bird
We have an '05 565 with 355 rears and we have consistent 5.2 mpg. I swear that whenever we run heavy (80,000 and above) that truck pulls better. If we load and hit a hill and pull it like there's no tomorrow, we stop in at the next CAT scale to check it out- never fails.
Weird, huh?
Not weird at all. I've found the exact same thing with my 565 Cummins. If I have a 20,000 lb load on, it seems to fight with hills. If I've got 44,000 in the box, it pulls like a champ. I think it craves the challenge. :wink:
For the record, I'm running a 565 with 3.55 rears and an 18 speed. I get about 5.75 out of mine when I'm not constantly idling.