correct operating temp. and sludge oil in air tank?

[cliff]

Have B61 with 653 engine,lot of miles but cranks with nothing but hot batteries in dead winter. Have replaced air compressor with factory rebuilt one but still getting about 1 third of cup of oil sludge after running about 6 hour trip. My thinking is with up-dated compressor this should be eliminated. The old 653 uses some oil,about 2 qts. on 400 miles pulling 26 ft. lowboy and 4500 lb. 2 cylinder JD tractor. Other question is what is correct temp. on heat guage running in mild weather with shutters operating okay. Temp. is now about 165 but I put a 165 degree thermostat in while back in top hose to keep cab warm quicker. Now I don't know if it should operate at higher temp. to get better service on engine.I'll remove thermostat if need be. Engine operates at 9 lb. while idling and 20-25 lbs. on road. I pulled pan 2 yrs. back and put 2 flat washers shimming up oil pump spring and got 4 more lbs. from this. Keeping it around 1800-1900 RPM, 50 MPH gets me there ande back without fail. any ideas on oil sludge from air compressor and idea if running too cool on heat guaage will be appreciated.