Wolftrk99

iTrader: (5)

Interesting, the dealer i worked at never brought that up and always had us put it in... learn somethingnew every day, have the tsb number on that??

MikeGyver

iTrader: (5)

I thought that it was common knowledge to not put additive in a G80. Maybe because of all of the searching for oil quantity and specs that I did in the fall when I replaced my differential cover.

someotherguy

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.

Wolftrk99

iTrader: (5)

Interesting, still bugging me it never got mentioned when i was at the dealership, and the fluid specs called for an additive, iirc!

therock

iTrader: (2)

I did the change and filled to a little less than 1" below the fill hole.
I checked the level before hand and it was a little lower.

Got the Mobil1, Gasket, and little pump from Advance..

Here is my magnet.

silver-mod-o

iTrader: (15)

With a G80, get whatever store brand BS junk oil that's on sale at the time. It's liable to end up all over the road anyway.

1994Vmax

iTrader: (4)

Local dummy dealership did that too..... and always wondered why the things never worked right lol. I mean they are junk regardless but still.... they usually lock up a couple times before they scatter.

Wolftrk99

iTrader: (5)

Usually the cross pins wear out before they scatter.

therock

iTrader: (2)

Mercy, are you guys talking normal conditions or under performance or abusive conditions?
Do you have mileage statistics?

Wolftrk99

iTrader: (5)

I have seen g80s with worn cross pns at 50-60k under "normal" conditions, have also seen trashed units at the same mileage, and occasionally have a few still going strong at 200k miles, sure once you start putting power to em and driving them harder it drastically shirtens the life... kinda the same effect of the auto trac on the front diff bearings when someone leaves it in auto 4wd year round, locking and unlocking constantly puts more strain in components and they give up the ghost! The g80 can be rebuilt, but its less expensive to replace it than to buy all the individual parts, and usually when the cross pin develops play the carrier is done anyway!!