Can anyone tell me a "normal" rear end oil temp while pulling 13K?
460/E4OD/4.10/215X85/16 tires. The last trip, I ran up around 250 pulling aganinst a head wind. At what temp does rear end oil break down? Thanks, Elliott

 

With flash points well over 400F, breakdown should not be a problem. I would be using synthetic for this application. Some oil companies claim that synthetic axle lubes greatly lower temperatures.

Jim

 

I have no idea what normal would be, but from reading it sounds like almost no one worries about rear end temperatures except for extreme or commercial applications.

Most good diff lubes are built to work fine without any worries about heat. Take a look at your fluid. It should be honey to maybe light brown color and it should not smell burnt, it should smell sulphury.

If you are really worried about it, I would recommend using synthetics, and you could look into finned high capacity covers. Usually these are for looks but they do help decrease the heat load.

I have seen pictures once in a great wheil of some application that actually has a small radiator kind of cooler, but usually that was for extreme loads.

Good luck and don't worry about it.

Jim Henderson

 

From www.mobil.com

"The exceptional chemical and thermal stability of Mobilube HD 80W-90 LS permits its use at intermittent bulk oil temperatures up to 149°C (300°F), with realistic drain and refill schedules. Steady operation temperatures above 260°F is not recommended without careful evaluation of lubricant drain intervals."

I would say you are getting close. Though with frequent changes I can't see any harm being done for short periods of time at 250 degrees. From working on tractors, I know the 250-280 zone is where you start to worry because the warnings are marked on the gauges there.