Friction modifier G80?

y2kgmc1500 · August 3, 2004

Do you need to use a friction modifier in the Eaton G80 locking diff? Have emailed Eaton and no response. Is it better to use synthetic or dino based fluid in these? What does it come from the factory with?

MyBigToy · August 3, 2004

GM says you don't need to use it.

bigdogs · August 3, 2004

I believe you are supposed to use synthetic as it is in there from the factory. I used Amsoil Series 2000 as it already has the friction modifiers in it and a lot cheaper than the GM grape juice

asilverblazer · August 3, 2004

Factory fluid is synthetic for the clutch packs. I wouldn't use anything but synthetic.

Valsport · August 3, 2004

Yes, definitely synthetic...I use Royal Purple Max Gear 75W-90. Also Amsoil and Mobil 1 are excellent.

bballa · August 3, 2004

I put mobil 1 in mine. Red line is also an option.

Smither · August 4, 2004

I sent an email to Eaton on this, specifying that I had a G80 code locker, and that as I understood it, no modifiers or additives were required for it, just straight synthetic fluid. My response back from them was, "Yes, that is correct".

Butch 02 Denali · August 4, 2004

All synthetic gear lube is rated GL5, for both posi and non posi use. It already has the correct friction additives. No more needs to be added.

BTW...Many are under the impression that the additives make the oil more slippery, but it is the opposite, the friction modifiers,(additives) REDUCE the slipperyness of the oil so the clutches grab better and don't slip.

Butch 02 Sierra Denali