Hey I got one, but it's for 8.5/8.625 ring gear!!

 

I just checked the RPO code for Limited Slip and the RPO code is G81 which is not on my car. Just G80 and GT4 for the axels

But the some say that a G80diff can be both a locking diff and a Limited Slip.

I spoke to a mechanic at GM here where i live and the first thing he said was to use 80-90 lubricant with additive.

But everybody i have talked to at different parts shops and mechanics tell me to use SAE 80-90 and add friction modifier when that is wrong.
Even a friend of mine that is a car mechanic and he have worked on several race cars for well known drivers here in Europe was sure that i needed to use GL-5 oil with additive as he said.

I am going to use Kendall NS-MP Hypoid gear lubricant, SAE 80W-90, GL-5 oil and not any friction modifier at all

I would have been so much more easy if GM could have written in the owners manual for G80 locking diff like they did for standard axle
Axle Lubricant use GM part no 1052271 or eqivalent like SAE 80W-90 GL-5

 

 

George,

I think this is the way to go. Part of the problem is the conflicting names for the types of differentials used in our trucks. People will use the words "locker", "posi" etc. interchangeably where in fact as we have discovered here the names and differences do matter.

For me I'm relieved that it looks like I've been doing the right thing all along!

Christine

 

Christine

Yes and mixing "additives" with "friction modifiers". The latter is the former but not necessarily the converse.

George

 

Some say friction modifier and others are much more used to add the little bottle with additive so they are the same thing....

A few days ago i sent an email to Eaton asking if i should add friction modifier or use oil that contains friction modifier on the rear G80 locking axle on a 1999 Blazer ZR2

Below is the reply i got from Eaton last night:
Hello
Thank you for your inquiry. Both synthetic and mineral based are sufficient. Although the G80 uses clutches, it is a full locker. If you use a friction additive this can reduce torque / load carrying capacity and is not recommended. As far as oil weight, please use the specified oil weight and quantity in your vehicles owner's manual. Eaton has no oil brand recommendation.

For further questions please contact technical support at 800 328 3850 or via live chat at eatonperformance.com

Thanks!
-Eaton Performance Support

 

Well, there you have it! Someone needs to write up what we have learned here and make the article for the general maintenance section.

I'm saving this info for my own reference for later!