Welcome!
It sounds like your 8v71 is pretty normal. How much oil do you use in say 500 miles? How is your speed on the flats?
Going up hills is a different matter, especially pulling a trailer or toad. They are just slow. Keep the rpms up and you'll make it to the top and watch your temps. Take a sample of your engine oil, dropbox and rear axle to a CAT dealer and have them run some tests. You can get a kit from them. Then you will know what's gong on.
Before we installed an 8v92T in our, 01 the 8v71 would maybe get 19 mph tops going up grades. I just waved as all other flew by.
