rear diff oil recommendations

[ATMINF]

I just ordered a rear diff aluminum cover and going to change out the fluid, what do you guys recommend? I am also pretty sure, but want to make sure 100%, on the rear diffs with the G80 locking diff you DO NOT add any friction modifier correct? Thanks!

[DaveH71]

I personally use redline with out friction modifiers but any 75w-90 will be fine, mobil 1, royal purple, etc. DO NOT add friction modifier to a g80. Redline has 2 separate kinds of 75w-90, one with friction modifiers and one without if you choose them. I have a g80 as well.

[00Silverado4x4]

I fully agree with Dave.

[kstruckcountry]

+2

[Z45]

No friction modifiers, those are for limited slip differntials which truck DO NOT use. You can use gear lube that is suitable for limited slip differentials, its the additive you are not supposed to use. Two completely different things.

 

AMSOIL Severe Gear 75W-90 or 75W-110. I would use nothing else. I have used it for years in my G80's, both car and trucks.

[jdubub]

AMSOIL all the way! As others have stated, DO NOT use additive.

[ATMINF]

Well finished the rear diff fluid change and new aluminum cover, also put on a Derale transmission pan (along with just a pan fluid change), also did the plugs and wires and also a oil change. Just got to hit all the grease points tommorow and the truck will good for a while.