Isx question

[heallen]

The truck has 240000 miles on it. It's usually or but on days it's not out it gets parked inside at night. So it get moved in and out everyday. Before I started working for him, the truck didn't have a driver for 5 months. Pretty sure it's a 550, 18 speed and it's not governed. Coming out of a B model Cat, I feel like it run pretty good. There are times when it doesn't really pulls the hills that good and times when it does OK. The fuel mileage is all over the board but generally wind/heavy load not matter how slow and easy I drive it 5.5 if I'm lucky. Light load and easy driving only gets me 6-6.4 at best.
What should manifold pressure be on a hard pill? It is 30 psi.
Oil gets changed every 10000 miles. Has an apu. I never idle it but I've only put 22000 miles on it personally.
I appreciate all the comments.