Rear differential gear oil additive

[bhorn0002]

I'm wanting to change the front and rear gear oil in my 2000 GMS Sierra 4x4. I hear some people say to use an anti-friction additive and others say not to. I believe that if you have the G80 rear differential you do not use it. How exactly do I determine if I have the G80 or not???

 

 

 

[txab]

RPO code in glove box. If G80 no additive is required

[bhorn0002]

I didn't see G80. Is there another initial that would indicate it's a limited slip differential?

[mjoekingz28]

Limited slips are for cars. We have (some of us) lockers.

 

This is what I have read and I cannot say for sure.

[Z45]

¨ Optional Equipment (G80 Order Code) on all GM two-wheel and four-wheel drive light trucks and sport utilities.

Benefits

¨ Improved traction differentiates the vehicle relative to other rear wheel and four-wheel drive vehicles on the market.

¨ Maintenance free; requires no lube additives.

¨ Enhanced towing and off-road performance.

¨ Patented carbon friction disc technology enhances performance and durability while reducing warranty claims.



Principles of Operation

¨ Wheel speed difference (left to right) in excess of 100 RPM will cause a flyweight mechanism to open and catch a latching bracket.

¨ The stopped flyweight will trigger a self-energizing clutch system, which results in the cam plate ramping against a side gear.

¨ Ramping increases until both axles turn at the same speed (full lock), which prevents further wheel slip.

¨ At speeds above 20MPH, the latching bracket swings away from the governor and prevents lockup from occurring.



Technical Specifications

¨ Automatic locking takes place within a fraction of a second, so smoothly that it is unnoticed by the average driver.

¨ Unlocking occurs automatically, once the need for improved traction is gone, and is unnoticeable to the average driver.

¨ Compatible with anti-lock brake systems.

[Z45]

I didn't see G80. Is there another initial that would indicate it's a limited slip differential?

No, G80 is the option, no G80 then no locker. Trucks do not use Limited Slip, those go in cars.

 

Note - 1999-01 models is was rare to find a G80 in them. Back in fall of 2000 I was looking to buy a 2001 Sierra E Cab with a G80. There was not one to be found on the locator within 500 miles.

 

 

 

[sdeeter19555]

I'm going to ask this...

 

Just because they state no extra additives, does this actually mean you have to use a fluid without LS additive? Or does it mean that the fluid used doesn't require extra additives (i.e, friction modifier) added to it?

 

To me that language indicates that no extra additives (i.e., friction modifier) is required...

 

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[Z45]

Your owners manual says to use GM 89021677 75W-90 Synthetic Gear Lube which has been superseded by 88900401 from what I can tell.

 

88900401 Synthetic Axle Lubricant GL-5 (75W-90)

 

PRODUCT DESCRIPTION AND FUNCTION: Product is a heavy-duty extreme pressure GL-5 axle lubricant. Withstands high temperatures encountered during extended high speed operation and heavy towing. Retains excellent fluidity at cold temperatures. It is a fully synthetic formulation with superior oxidation and thermal stability. Product has a long fluid life with a grape scent.

 

Does not say it contains any friction modifier (LS Additive) in the product description or on the label

 

Source AC Delco Product Catalog.

 

 

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Then there is this for limited slip................

 

88862624 Dexron LS Gear Oil 75W-90 Synthetic EP Gear Lube with Limited Slip Additive

 

 

You be the judge....

 

 

 

 

.

[Z45]

#PIP4054D: Eaton Locking Differential Chatter Shudder Noise On Turns - (Jul 19, 2010)

Subject: Eaton Locking Differential Chatter Shudder Noise on Turns


Models: 2004-2007 Buick Rainier

2000-2011 Cadillac Escalade, ESV, EXT

2002-2011 Chevrolet Avalanche

2004-2011 Chevrolet Colorado

2003-2009 Chevrolet Express

2000-2011 Chevrolet Suburban, Tahoe

2000-2007 Chevrolet Silverado Classic

2007-2011 Chevrolet Silverado

2002-2009 Chevrolet Trailblazer

2004-2011 GMC Canyon

2002-2009 GMC Envoy

2000-2011 GMC Yukon, Yukon Denali, Yukon XL

2000-2007 GMC Sierra Classic

2007-2011 GMC Sierra

2003-2011 GMC Savana

Equipped With a Locking Rear Differential RPO G80




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This PI was superseded to update model years. Please discard PIP4054C.


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The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:
Customers may comment on a chatter or shudder from the rear axle on vehicles equipped with an Eaton locking differential. This condition would be noticed in parking lot maneuvers, turning, or during locking differential engagement and may be more noticeable when the differential is hot. Locking differential clutch chatter may be causing this concern.

Notice: This does not apply to vehicles equipped with RPO QS4 (Quadrasteer) which is part of option package NYS. Quadrasteer vehicles use Dana axles and have a different fluid requirement.

Notice: This PI does not apply to vehicles equipped with a RPO G86 limited slip differential.

Recommendation/Instructions:
If differential clutch chatter is encountered in a vehicle equipped with an Eaton locking differential, flush, drain and refill the differential with new synthetic fluid, use the fluid part number listed in SI for the vehicle currently being worked on. If the condition returns, replace the rear differential clutch This PI was superseded to update model years. Please discard PIP4054C. plates and refill the differential with new synthetic fluid, use the fluid part number listed in SI for the vehicle currently being worked on. Refer to eSI for clutch plate replacement and set up procedures.

Notice: Eaton locking differentials used in 10.5[Prime ] rear axles are equipped with steel clutch plates. It is a design characteristic of these steel clutch plates to exhibit more clutch chatter than other models.

Important: Installing any friction modifier causes the clutch pack in the locking differential to slip and miss engagement. A fluid flush can often remove debris that is a contributor to clutch chatter. Adding friction modifier additive can cause a loss of locking differential functionality.

Notice: On Quadrasteer equipped vehicles, simply flush the rear axle and refill with the fluid listed in SI document 793720 under the steerable application.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.

[sdeeter19555]

Again, that's "adding friction modifier".

 

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[Sierra Boy]

 

 

This is a good vid

 

Sierra Boy

[Z45]

Again, that's "adding friction modifier".

 

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A gear lube with the LS additive in it is the wrong lube for a GM truck.

 

Show me in your owners manual where is says to use a gear lube with an LS additive.

[sdeeter19555]

A gear lube with the LS additive in it is the wrong lube for a GM truck.

 

Show me in your owners manual where is says to use a gear lube with an LS additive.

Show me where is says a non-LS gear lube?

 

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[sdeeter19555]

Not being difficult, but it's no different than the confusing language about Dexos oil usage...it doesn't say the gear oil can't be for an LS, only that adding friction modifier is bad.

 

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[mj0528]

 

 

This is a good vid

 

Sierra Boy

That is a good vid. Crazy that some of the other 4x4 couldn't make it up the hill. Is tjey g80 that much better than the competitors locking diff or was than an exaggerated?

 

 

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