Originally Posted by SnowDrifter
Originally Posted by StevieC
If one of the wheels spins in opposite direction to the other when you turn it by hand, you don't need the slip-lock additive. That's the easiest way to tell if you don't know off hand. (some vehicles have to be in neutral for this and obviously with the parking brake not applied)
This is what I did to find out for my Highlander when I drained and refilled with the Severe Gear.
Do this before you drain your old fluid out.
I think it's worth noting that this isn't necessarily always accurate. For example the G80 in my truck needs a limited slip additive. It's a clutched locker that needs a speed differential to well.. Lock up. It needs it, and will spin wheels in opposite directions on jackstands
@OP, it should say in your owners manual under fluid specifications
The G80 does not use clutch discs to control wheel spin. It uses a pawl mechanism that activates based on excessive wheel spin on one side for a solid mechanical lock up. See a demonstration here:
https://www.youtube.com/watch?time_continue=103&v=mk5RAC8qpyo
No additive is needed per GM.
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.
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