G80 needs LS additives or not?

Interleukin6 · September 30

Hi, My rear differential is GM (SU8 with G80 positraction limited slip & GU6 3.42 ratio). I am about to change the differential fluid. Is ACDelco 10-4122 (GM 19368514) 75W-85 DEXRON Low Viscosity Gear Oil right one? I’ve read some say G80 needs LS additives or others say “no”. I think G80 doesn’t need additives but please confirm it for me. Thank you.

redwngr · September 30

Never put LS additives in a G80

G80 is not a 'positraction limited slip'.

G80 is a locker.

Edited September 30 by redwngr

Interleukin6 · October 1

Please educate me further. I can’t play YouTube you linked for some reason now. The description of G80 I got from my dealer is “axle, rear, positraction, limited slip” What am I missing? Thank you.

CamGTP · October 1

It doesn't use clutches to lock the wheels when it loses traction. It's a mechanical locker that uses weights to throw out and engage the locker. You can use the google if you want to read up on how it works.

Regular synthetic gear oil is all that is required.

Interleukin6 · October 1

Thank you so much!

kickass audio · October 1

As mentioned you don't need additive for the fluid. I will say I had a hard time finding the correct viscosity for the diffs that didn't have LS additive added to it from the factory. I put 75w-90 into both the front and rear diffs on my old 2014 and it worked just fine. I ran it with that fluid in it for 3 years and had no problems with chatter and the locker worked the same as it did from when I bought the truck used.

I could be wrong but I don't see any problem using fluid with the additive on a diff that doesn't require it. It's if you use normal fluid on a limited slip diff that you have a big problem.

txab · October 1

16 hours ago, kickass audio said:

As mentioned you don't need additive for the fluid. I will say I had a hard time finding the correct viscosity for the diffs that didn't have LS additive added to it from the factory. I put 75w-90 into both the front and rear diffs on my old 2014 and it worked just fine. I ran it with that fluid in it for 3 years and had no problems with chatter and the locker worked the same as it did from when I bought the truck used.

I could be wrong but I don't see any problem using fluid with the additive on a diff that doesn't require it. It's if you use normal fluid on a limited slip diff that you have a big problem.

If you add additional friction modifiers to a G80 you'll induce issues such as improper engagement etc.....