I just got a shiny new Mag Hytec diff cover for the rear of my 2005 dually 6sp manual. I tow heavy most of the time now.. big truck camper plus an enclosed trailer. Wondering if I should use 75W90 or 75W140? And should I use "shockproof" or not?

Thoughts?

Rob

 

I have had an '03 DRW since new. I tow a 40' fiver. At the first factory change I have used 75w-140 Mobil 1. Have changed it several times since and it now has 263,000 on the clock.

 

I put in Redline 75-90, but if i towed heavy,,, i would run 75-140 Like Bob does.