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Info - Rear Axle Lubricant Compatibility and Usage

Subject:Rear Axle Lubricant Compatibility and Usage

Models:1988-99 Chevrolet and GMC C/K, G Van and P1-3 Series Models
1999 Cadillac Escalade
Built after the VIN Breakpoints (C/K) listed below:



This bulletin is being revised to add the 1999 Model Year, VIN Breakpoint information, and additional text. Please discard Corporate Bulletin Number 86-42-04 (Section 4 - Driveline/Axle).


Plant

Make

VIN Breakpoint

Arlington

Chevrolet

(Pickup)

XR703077

Arlington

Chevrolet

(Pickup)

XR703078

Arlington

Chevrolet

(Tahoe-4 Dr)

XR148860

Arlington

Cadillac

(Escalade)

XR409680

Arlington

GMC

(Pickup)

XR703184

Arlington

GMC

(Pickup)

XR703113

Arlington

GMC

(Yukon-4 Dr)

XR516469

Arlington

GMC

(Denali)

XR914788

Flint

Chevrolet

(All)

XF062378

Flint

GMC

(All)

XF062366

Janesville

Chevrolet

(All)

XJ471026

Janesville

GMC

(All)

XJ771410

Silao

Chevrolet

(Tahoe-2 Dr)

XG206200

Silao

Chevrolet

(Tahoe-4 Dr)

XG206323

Silao

GMC

(Yukon-4 Dr)

XG534060

This bulletin is being issued to inform dealers about the compatibility and usage of the new Fuel Efficient SAE 75W-90 Synthetic Axle Lubricant, GM P/N 12378261 (In Canada use P/N 10953455), with current axles, and with the non-synthetic axle lubricant, GM P/N 1052271 (In Canada use P/N 10950849), for the rear axles on the above light-duty trucks.

Testing has shown that the new synthetic lubricant will chemically attack the Room Temperature Vulcanizing (RTV) sealant. Use only the non-synthetic lubricant, P/N 1052271, in axles using RTV sealant (See 9.5 and 10.5 information below).

American Axle and Manufacturing (A.A.M.) has approved the use of the new Fuel Efficient SAE 75W-90 synthetic axle lubricant for rear axles with the following restrictions:

    • All 8.6 inch axles are compatible as originally built.
    • 9.5 inch axles on vehicles built prior to mid-February 1998 are NOT compatible because RTV sealant is used on the cover pans.
        On vehicles built after mid-February 1998 and equipped with 9.5 inch rear axles, synthetic lubricant, P/N 12378261, can be used because the RTV was replaced with a gasket. Other mid-February changes to the 9.5 inch rear axles include a new cover pan and cover pan fasteners common to other axles.

       Important: The new cover pan is not retrofittable to the housing of 9.5 inch axles on vehicles built prior to mid-February 1998. A new retrofit kit is available that will enable the use of synthetic lubricant for vehicles built after mid-February, 1998.

    • All 10.5 inch axles prior to March 3, 1999 are compatible if the axle shaft hub seal (RTV) is replaced with P/N 327739 gasket when changing to synthetic lubricant.

As a product improvement, this new lubricant has been released into 1999 current production C/K vehicles built after the above VIN breakpoints (Except HD3500 models which use 75W-140 synthetic lubricant, P/N 12346140).

It is recommended that synthetic lubricant be used when changing rear axle lubricant for the following reasons:

    • Potential fuel economy
    • Lower operating temperature under severe usage conditions

Important: 

   • You do not need to wash/rinse any non-synthetic lubricant from the axle cavity when changing over to a synthetic lubricant. However, you should remove debris from the magnet and the bottom of the axle cavity whenever the axle fluid is changed.
   • On light-duty trucks equipped with locking differentials, do NOT use a limited-slip additive.

Parts Information

P/N

Description

Quantity

327739

Gasket, Axle Shaft Seal

1

12378261

(In Canada use P/N 10953455)

Fuel Efficient SAE 75W-90 Synthetic Axle Lubricant

1

1052271

(In Canada use P/N 10950849)

Non-Synthetic Lubricant

1

12471310

Kit, 9.5 Inch Axle Cover Pan

1

Parts are currently available from GMSPO.