Correct gear oil for G80 locker

[Matthew Jeschke]

Anybody know from the factory service manual or other reputable source...

Q1. The gear oil spec needed for the G80 locker in a GMT800 chassis?
Q2. Also how many quarts for front and for rear diffs?

My friend needs some help to service his 2005 Z71 truck and I want to make sure we get the correct fluid. I know there's clutches in the G80 contrary people are saying in other forums who are specifying gear oil.

My Chilton doesn't get that specific (only specifies 75W90 Synthetic) and my All Data subscription expired.

Thanks!

 

[Fless]

Be sure to crack open the FILL plug on the front diff before you drain it; just make sure it can come out.

For capacities take a look at the link below; hopefully it helps but it's for a Tahoe and you said truck, so just to be sure navigate to the correct vehicle using the links at the top of the browser window:

Fluid - Differential — 2005 Chevrolet Tahoe 4WD V8-5.3L VIN T Service Manual | Operation CHARM

Detailed repair manual for the 2005 Chevrolet Tahoe 4WD V8-5.3L VIN T.

charm.li

The look through this short thread:

2014 Yukon XL Denali

What type of fluid is recommended for rear differential on my 2014 Yukon Denali. Is this a good choice? https://www.autozone.com/greases-and-gear-oil/gear-oil/mobil-1-75w-140-synthetic-gear-oil-1-quart/706574_0_0 TIA.....want something I can P/U locally.

www.tahoeyukonforum.com

 

[swathdiver]

Anybody know from the factory service manual or other reputable source...

Q1. The gear oil spec needed for the G80 locker in a GMT800 chassis?
Q2. Also how many quarts for front and for rear diffs?

My friend needs some help to service his 2005 Z71 truck and I want to make sure we get the correct fluid. I know there's clutches in the G80 contrary people are saying in other forums who are specifying gear oil.

My Chilton doesn't get that specific (only specifies 75W90 Synthetic) and my All Data subscription expired.

Thanks!

Front is 1.51 Quarts of SAE 80W–90 GL5 Lubricant
Rear is 2.15 Quarts of 88900401 or equivalent meeting GM Specification 9986115