Rear Axle and Posi-trak fluid

[Dakster]

Do the new trucks (2007 LMM's) require the addition of posi-trak fluid to the rear diff when changing the oil out? I didn't see it mentioned anywhere in the manual, but when I changed mine out it smelled like it had some in it. (That unmistakeable smell)

I just changed the oil out of the rear after 3k miles. Wow... it was very full of metal and the magnetic drain plug was caked with metal particles.

Thanks

[Idle_Chatter]

No friction modifier additive is required for the Eaton gov-lock unit in your differential - only a GL-5 rated synthetic lube.

[Dakster]

Thanks for the help! I used Mobil 1 Synthetic 75-90... On the bottle it says "where API GL-5 is required..."