I own a 1997 F250 Ford 4x4 7.3 liter powerstroke diesel that I bought new. It now has 78,000 miles on it. I get average 17 MPG highway. Just bought a fifth wheel camper, weighing about 8500 lbs. Just want to know what I can do to get better fuel mileage with this truck and maybe a little more power. I just flushed the transmission fluid and the mechanic said it was very clean. I just want some tips on this truck. And something that is not going to cost a lot of money.

Use SAE 5W-40 full synthetic heavy duty diesel oil.

Use Mobil 1 Multi-Vehicle Synthetic ATF in the transmission and power steering system.

Use Mobil 1 Synthetic Gear Oil in the differential.

Together, these suggestions should increase gas mileage by 8 to 10%.

:)thank you for the tips! I will do them. Also will it help to straight pipe the exaust? And is this one of the better diesel motors out there? Or should I update?
Use SAE 5W-40 full synthetic heavy duty diesel oil.

Use Mobil 1 Multi-Vehicle Synthetic ATF in the transmission and power steering system.

Use Mobil 1 Synthetic Gear Oil in the differential.

Together, these suggestions should increase gas mileage by 8 to 10%.

Look into the oils and bypass filter mentioned in the link below:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-8.html#post1415281

I think the 7.3L PSD is the best diesel engine Ford has ever made. I'd save your money on the exhaust.

You should sell it to me and buy a Honda.