I had a post over the weekend asking whether or not I should add posi additive to the gear oil in my Borg-Warner 9-Bolt Posi. The reason I was asking was the additives all clearly stated that it was for clutch and plate-type posi units. The 9-bolt posi units are cone type. The response was that I should put the additive in. This may be incorrect. I have checked my Owner's Manual and here is what it says in the section titled "Rear Axle - Limited-Slip Differential": "Refill to the level of the filler plug hole (on the passenger's side of the differential case) with special gear lubricant GM Part No. 1052271 or 1052272 or equivalent, with the exception of the following: 1) Vehicles equipped with the L98 (5.7L) engine. 2) IROC model vehicles equipped with LB9 (5.0L TPI) engine, manual transmission and rear disk brakes. The axles in these vehicles require gear lubricant GM Part No. 1050010 or equivalent. NOTE: Additives are not recommended for Camaro axles" Basically, the above 2 items refer to the 9-Bolt cars. I find the "NOTE" most interesting. Last November, I had the gear oil changed in my rear end and now the posi only works under light load (rain). In the dry, I have a one-legged monster. I do not know if this is a coincidence or not. Between Christmas and New Years, I plan to change the rear end gear oil again - WITHOUT additive. I have already purchased Red Line Oil, but I am also going to check out the GM oil described above. Anyone else know about this obviously obscure item? If so, is it possible that this additive may be contributing to my posi unit not working optimally?

Last time I bought some rear gear oil, the parts guy at the Pontiac dealership almost screwed up. It is supposed to come in a SINGLE bottle (I knew this from the 30k change). Other posi's have the oil PLUS a bottle of additive. Oil for the B/Ws is unique.

Bulletin No.: 76-02-02A

Date: October, 1998

INFORMATION

Subject:
Recommended Axle Lubricant


It says not to use an additive.

This bulletin is from GM, so your dealer can look it up for you.

Here's some more info from another TSB -

Number 87-4-1 Date 12/86

Subject: LIMITED SLIP REAR AXLE LUBRICANTS


ALL 1987 REAR DRIVE PASSENGER CARS WITH LIMITED-SLIP DIFFERENTIALS

Several changes have been made to the limited-slip rear axle lubricant service change recommendations.

The following information may not be reflected in all 1987 service manuals, update as necessary.

LIMITED-SLIP DIFFERENTIAL LUBRICATION

MODEL APPLICATIONS LUBRICANT ADDITIVE

Safari Wagon All 1052271 1052358

Grand Prix All 1052271 Do Not Use

Firebird Rear Disc Brakes 1050010 Do Not Use

Firebird All Others 1052271 Do Not Use

This is all I could find...


INFO ON RECOMMENDED AXLE LUBRICANT #76-02-02A
REVISION: 09/25/98 DIVS INVL 1 2 3 4 5 6 7

THIS BULLETIN IS BEING REVISED TO ADD THE 1998 AND 1999 MODEL YEARS AND ADD VEHICLE LINE AND RECOMMENDED AXLE LUBRICANT INFORMATION. PLEASE DISCARD CORPORATE BULLETIN NUMBER 76-02-02 (SECTION 0 - GENERAL INFORMATION). ______________________________________________________________________

SUBJECT: INFORMATION ON RECOMMENDED AXLE LUBRICANT

MODELS: 1999 AND PRIOR REAR WHEEL DRIVE PASSENGER CARS, LIGHT AND MEDIUM DUTY TRUCKS, AND FOUR WHEEL DRIVE VEHICLES

THE FOLLOWING TABLES PROVIDE THE LATEST INFORMATION ON RECOMMENDED AXLE LUBRICANT.

REAR AXLES WITH NON LIMITED-SLIP OR NON LOCKING DIFFERENTIALS

VEHICLE LINE & RECOMMENDED AXLE LUBRICANT:


1994 THROUGH 1997 CAMARO AND FIREBIRD AND GEO (CHEVROLET) TRACKER
GM P/N 12345977 OR AN SAE 80W-90 GL-5 GEAR LUBRICANT

1998 AND 1999 CAMARO AND FIREBIRD
GM P/N 12378261, SAE 75W-90 SYNTHETIC AXLE LUBRICANT

HD-3500 TRUCKS (DANA 11.0" AXLES)
GM P/N 12346140, SAE 75W-140 SYNTHETIC GEAR LUBRICANT

CADILLAC CATERA
GM P/N 12345977 OR AN SAE 80W-90 GL-5 GEAR LUBRICANT

1999 GMT 800 TRUCKS
GM P/N 12378261, SAE 75W-90 SYNTHETIC AXLE LUBRICANT

ALL OTHER NON LIMITED-SLIP OR NON LOCKING DIFFERENTIALS INCLUDING B AND D CARS, S/T, M/L, G, P, AND C/K TRUCKS EXCEPT GMT 800 TRUCKS, AND AS NOTED ABOVE
GM P/N 1052271 OR AN SAE 80W-90 GL-5 GEAR LUBRICANT

REAR AXLES WITH LIMITED-SLIP OR LOCKING DIFFERENTIALS

VEHICLE LINE & RECOMMENDED AXLE LUBRICANT:

1994 THROUGH 1997 CAMARO AND FIREBIRD, 1998 OR OLDER CHEVROLET CORVETTE
USE ONLY GM P/N 12345977 PLUS 4 OUNCES OF GM P/N 1052358 LIMITED SLIP ADDITIVE

1998 AND 1999 CAMARO AND FIREBIRD, 1999 CORVETTE
GM P/N 12378261, SAE 75W-90 SYNTHETIC AXLE LUBRICANT. WITH A COMPLETE DRAIN AND REFILL, 4 OUNCES OF GM P/N 1052358 LIMITED SLIP ADDITIVE

1996 AND OLDER B AND D CARS, AND 1993 AND OLDER CAMARO AND FIREBIRD
USE ONLY GM P/N 1052271 PLUS 4 OUNCES OF GM P/N 1052358 LIMITED SLIP ADDITIVE

1999 GMT 800 TRUCKS
GM P/N 12378261, SAE 75W-90 SYNTHETIC AXLE LUBRICANT (DO NOT ADD LIMITED SLIP ADDITIVE)

ALL OTHER LIMITED-SLIP OR LOCKING DIFFERENTIALS INCLUDING C/K (NON GMT 800), S/T, M/L, G TRUCKS
USE ONLY GM P/N 1052271 (DO NOT ADD LIMITED SLIP ADDITIVE)

MEDIUM-DUTY TRUCKS (TOPKICK, KODIAK, ETC.)

VEHICLE LINE & RECOMMENDED AXLE LUBRICANT:

MEDIUM DUTY TRUCKS
GM P/N 12345841, SAE 75W-90 SYNTHETIC AXLE LUBRICANT FOR MEDIUM DUTY TRUCKS (EATON ROADRANGER AXLE LUBRICANT)

FRONT AXLES ON 4-WHEEL DRIVE VEHICLES

VEHICLE LINE & RECOMMENDED AXLE LUBRICANT:

FRONT AXLES IN 4-WHEEL DRIVE VEHICLES OTHER THAN GEO (CHEVROLET) TRACKER
GM P/N 1052271 OR AN SAE 80W-90 GL-5 GEAR LUBRICANT

FRONT AXLES IN 4-WHEEL DRIVE VEHICLES IN COLD CLIMATES WHEN EXCESSIVE SHIFT EFFORT IS REQUIRED TO SHIFT INTO 4-WHEEL DRIVE
GM P/N 12345836, SAE 75W-90 SYNTHETIC COLD CLIMATE FRONT AXLE LUBRICANT

GEO (CHEVROLET) TRACKER
GM P/N 12345977 OR AN SAE 80W-90 GL-5 GEAR LUBRICANT

PARTS INFORMATION:

PARTS ARE CURRENTLY AVAILABLE FROM GMSPO.

FIGURES: 00 ATTACHMENTS: 00

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 1998 GENERAL MOTORS CORPORATION. ALL RIGHTS RESERVED.

© Copyright General Motors Corporation. All Rights Reserved.

Holy Cow!

To summarize the above posts in chronological order:

December 1986 - Do not use 1050010 (Firebird only!?)
September 1998 - Use only 1052271, plus additive 1052358
October 1998 - Do not use an additive

Is this correct? Are we confident this is relevant to the 9-bolts? Or is this a general statement? If you use the information in order, then:

You should use 1052271 (September 1998) without additive (October 1998).

... bottom line is you don't need the additive.

Just to close this out...

I spoke with a fellow autocrosser, F-body owner and Chevy parts manager (all one guy). He told me that the additive is really only there to reduce noise. In addition, he has a rear end like ours and has put the additive in his rear end even though the TSB's say otherwise. Finally, he also said that the Red Line Oil that I bought would be fine and other autocrossers (on the National Level) have told him that the Red Line Oil reduces noise and helps the posi work better in the turns (inner wheel), without the need for the additive.

So, I am adding the Red Line Oil, without the additive based on the research that I have done.

We'll see if the rear end is really burned out. My "advise" told me it is probably toast...

I have used REDLINE gear oil in my 9bolt for many years and still lays two stripes after 81,000 HARD miles.

For what its worth -

I bought some Red Line oil for my diff. many years ago. I never put it in. I spoke with someone from Red Line at the time and they told me the oil would improve the friction in the cones - to a point where normal street driving around corners would be affected. He said the diff would heat up and the cones would fail eventually. Their oil should only be used in hi-perf. applications where performance comes before longevity. This was over ten years ago. Maybe they've changed their formula. Food for thought, anyway.

Greg, check out www.mfba.org

We have lots of thirdgen owners there too!

interesting!!!!!