What to do with rear end?

[Supercharged111]

Well WTFO? I would think a GL5 is a GL5, limited slip additives notwithstanding.

 

[df2x4]

Well WTFO? I would think a GL5 is a GL5, limited slip additives notwithstanding.

My thoughts as well, and it has no such additives so I see no reason to worry.

 

[CrustyJunker]

Well WTFO? I would think a GL5 is a GL5, limited slip additives notwithstanding.

Agreed. And what else is strange? After consulting the Google - The "VehicleCare," labeled bottles don't mention the passenger car thing.

You must be registered for see images attach

Sorry it's kind of potato quality, but it's zoomable. I'll see if I still have an empty or used bottle laying around in the garage to double-check.

 

[Schurkey]

This is a GM Canada bulletin; note that the part number specified (10950849) was not/is not valid in the USA.

(See below)

LOCKING DIFFERENTIAL LUBRICANT (SERVICE INFORMATION) #91-4-109
SUBJECT: LOCKING DIFFERENTIAL (G80) LUBRICANT - (SERVICE INFORMATION)
VEHICLES AFFECTED: ALL LIGHT TRUCKS EQUIPPED WITH G80 REAR AXLE ALL YEARS
Some light duty trucks equipped with locking rear axles (G80) may exhibit rear axle chatter, especially when turning a corner from a stop.
This condition of alternate engagement and disengagement of clutches in differential assembly is usually caused by contaminated axle lubricant.
To correct this condition, drain and refill the rear axle with SAE 80W-90 GL5 (P/N 10950849).

The use of any additive in locking rear axles (G80) is not recommended. Rear axle additives are designed for use in limited slip differentials which are normally installed in cars. All light duty trucks equipped with RPO G80 make use of a locking differential and the use of additives will delay the engagement of the locking mechanism and may decrease axle life.

VEHICLES/COMPONENTS INVOLVED: Some light duty trucks equipped with locking rear axles, RPO G80.

SERVICE PARTS INFORMATION:
Part Number Description
10950849 Lubricant, Rear Axle (1 litre)

Parts are currently available through CANSPO.
WARRANTY INFORMATION:
As specified in Light Duty Truck Maintenance Schedules, locking rear axle fluid drain and refill is required owner maintenance at the first engine oil change. Failure to drain and refill the rear axle as specified may contribute to a later axle chatter condition. Refer to the appropriate Light Duty Truck Maintenance Schedule or service manual, section OB, for further details on change intervals.
General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.
© Copyright General Motors Corporation. All Rights Reserved.

10950849 is the Canadian equivalent to 1052271 in the USA. From this next bulletin:

Info - Rear Axle Lubricant Compatibility and Usage #99-04-20-001 - (06/18/1999)
Rear Axle Lubricant Compatibility and Usage
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).


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.



GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer"

SO: The GM synthetic axle grease in use in 1998 will chemically attack the RTV Silicone sealer GM used in 1998. I have no knowledge of incompatibility between OTHER synthetic greases, or OTHER RTV Silicone sealers.

GM SAYS if you have an 8.6 (what I've been calling an 8.5") axle, you can use synthetic grease. OR you can use non-synthetic. They suggest the synthetic for improved fuel economy and lower axle temperature.

GM SAYS if you have a 9.5" rear axle made before the switch to paper gasket on the axle cover...you CANNOT use synthetic grease. Again, there's no mention of other RTV silicone sealers, non-GM synthetic grease, and "GM" doesn't have a suitable paper gasket. Who knows what the aftermarket has, though.

GM SAYS if you have a 10.5" rear axle, you can use synthetic if you have paper hub gaskets instead of RTV silicone.

NOW we just have to find what part numbers superceded the ones in the bulletin. For fukk sakes, GM. Why the need for multiple versions of friggin' axle grease? Could this be any more complicated?

Continued.

 

[Schurkey]

The synthetic grease 12378261 or 10953455 crosses to the "Grape Scented" 89021677 or AC-Delco 10-4016.

The NON-Synthetic axle lube 1052271 or 10950849 may have been replaced with 89021671, Delco # 10-4052 but that's a GL-4 lube, and apparently it's also been discontinued. This is where I lose the trail of a compatible non-synthetic grease.

Someone--or several someones--at GM need a hearty ass-kicking.

I'd appreciate it if someone could verify these numbers. I'm goin' cross-eyed trying to find the superceded part numbers.

 

[df2x4]

Agreed. And what else is strange? After consulting the Google - The "VehicleCare," labeled bottles don't mention the passenger car thing.

You must be registered for see images attach

Sorry it's kind of potato quality, but it's zoomable. I'll see if I still have an empty or used bottle laying around in the garage to double-check.

The lack of the "not for use in trucks" warning on the updated packaging leads me to believe that whatever the issue was which required it at one time is no longer a widespread problem.

 

[df2x4]

The synthetic grease 12378261 or 10953455 crosses to the "Grape Scented" 89021677 or AC-Delco 10-4016.

The NON-Synthetic axle lube 1052271 or 10950849 may have been replaced with 89021671, Delco # 10-4052 but that's a GL-4 lube, and apparently it's also been discontinued. This is where I lose the trail of a compatible non-synthetic grease.

Someone--or several someones--at GM need a hearty ass-kicking.

I'd appreciate it if someone could verify these numbers. I'm goin' cross-eyed trying to find the superceded part numbers.

That all seems correct to me based on a quick Google search.

Would you mind sharing your theory on why the GM 89021669 (ACDelco 10-4051) may not be correct for these trucks other than the warning on the bottle? Like I mentioned in my last post the lack of that warning on the updated packaging makes me think it's probably no longer relevant.

 

[Schurkey]

My concern was with the warning on the bottle, which was repeated in another service bulletin.

The way GM changes part numbers, you'd think if there'd been a change in the "formula" for that gear grease, they'd have updated that part number, too.

But then, who else has heard of synthetic gear lube "corroding" RTV Silicone? I'm still skeptical. GM does some weird stuff.

Hence the "hearty ass-kicking" required.

 

[df2x4]

My concern was with the warning on the bottle, which was repeated in another service bulletin.

The way GM changes part numbers, you'd think if there'd been a change in the "formula" for that gear grease, they'd have updated that part number, too.

But then, who else has heard of synthetic gear lube "corroding" RTV Silicone? I'm still skeptical. GM does some weird stuff.

Hence the "hearty ass-kicking" required.

It makes me wonder if maybe GM dealerships were using a particularly crappy formula of RTV at one time. Maybe they changed their RTV and the gear oil stayed the same.

 

[Supercharged111]

How many people are using RTV from 1998? If that's the only variable then I'd say to hell with it. What a lame ass thing to cause a lube formula change. Use different RTV.