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G80 Gear Lube - Eaton phone call today


FL335i

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Posted

Figured I'd share. The net is full of discussion on what type of oil the G80 rear ends need. Syn vs Dino, LS vs non LS. Well I finally got around to calling Eaton's diff tech support. Very helpful guy. He clearly explained the G80 is not supposed to have LS friction modifiers. It does have clutches that operate the locker. The 75w-90 Syn is fine. So M1, Valvoline etc at the parts stores all have LS friction modifiers. I'm actually looking at buying this http://www.phillips66lubricants.com/documents/conoco/industrial_oils/FOB%20Triton%20Synthetic%20Gear%20Lube%20TDSw%20778906.pdf

 

 

I can buy it for about $150/Pail. I can do my '14's front and rear diffs and I have my 89 K5 Jimmy I'm restoring which has two straight axles. Much cheaper than the store 1L bottles. Plus I cannot find 75/90 Syn gear oil locally w/out LS additives.

 

 

EDIT: The above link is the 80-40 Triton oil. I'm going to buy a pail of the 75w-90 FE gear oil. Correct Data sheet link: http://www.phillips66lubricants.com/documents/conoco/industrial_oils/FOB%20Triton%20Syngear%20FE%20TDSw%20828151.pdf

Posted

Interesting that the clutches are not supposed to have friction modifiers. Amzoil Severe Gear is approved for the G80 and front axle on our trucks. Phillips/Conoco also makes very high quality products. I would have no issue using their GL5 full synthetic product.

Posted

Gm has only had a bulletin out for the better part of 2 decades about proper oil with the old gov bomb. It's funny that in its 43 years of production even most dealers are clueless of what to use for oil in it lol.

 

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Posted

I have to say, I've never been a fan of the G80 but it seems they've improved them in recent years. In the old days it was a "one wheel peel" for quite a while until the G80 would "kick in" locking violently. With the 2014, it feels much more like a standard LSD--never letting one wheel spin too much before you can feel the other getting torque. It seems to work well enough I'm not in as big a hurry to get rid of it.

 

They had a bad rep for durability, especially in smaller axles, but these for the 9.5/9.76" are all new so I think that's largely unknown for these particular units. It has been more than two years now and there doesn't seem to be a bunch of posts from people who have broken their diffs.

Posted

Every now and then mine refuses to lock up right away and make a bunch of ugly grinding noises. I'd get it checked out at the dealer but secretly I'm hoping it gets bad enough to motivate me to replace it and regear. I have my eyes on a Detroit Tuetrac.

 

It's probably my fault. I've beat on it fairly hard the last couple years.

Posted

Gm has only had a bulletin out for the better part of 2 decades about proper oil with the old gov bomb. It's funny that in its 43 years of production even most dealers are clueless of what to use for oil in it lol.

 

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That's because the average owner and mechanic don't know the difference between a G80 limited slip differential and an G80 mechanical locking differential. That plus the fact that GM uses the same G80 rpo code for both, which adds to the confusion. Limited slip differentials (aka Posi) are normally installed in performance cars. The only truck to ever get one (known as RPO G86) is the Quadrasteer, QS was a Dana axle. A locker was inappropriate for the QS.

 

Here is the SPID label from my 2009 CTS, note G80, Limited Slip Differential because no car gets a locker.

da8939d6-7af3-4838-a7ee-5954e36d4698_zps

 

2012 GMC pu, note G80

DSC00004.jpg

Posted

#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

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

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 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 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.



Posted

The reason I know and have this information stems back to the mid 90's when I had an incident with a Chevy dealer who insisted they needed to add a limited slip additive (and change me a confiscatory fee) to my truck G80 rear axle when I had them R & R the gear lube with my own preferred brand. The mechanic and SM insisted I did not know what I was talking about so I was out to prove them wrong. Long story short, I did and they had to eat crow and flush out my rear axle on my truck. Never been back to that dealer since and never will.

Posted

I don't like stuff that shock loads to engage.... and has a normal state of being open.... not to mention i want my rear end locked above 25 mph..... My 9.76 version operates like a gov lock from 1973 and bangs itself to lock.... It probably will never break based on physical size but it's the only thing in the truck I actually want to put in a metal bin. However being I have the 9.76" setup, and how pathetically slow the aftermarket is going about things even for the 9.5", I don't forsee the aftermarket ever making carriers for it so I doubt I will own the truck long enough to change it..

 

But back to the thread yes just standard synthetic gear oil with no clutch additives is all it needs.

 

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Posted

Not sure how much the G80 has changed over the years since mine is an older model. So far it still works great and engages like it supposed to when out in the wet grass, or farm fields. 160k miles using AMSOIL's Severe Gear 75w-90 fluid in front and rear. I switched it out when I purchased the truck new and after putting about a thousand miles on it.

 

Maybe I'm on borrowed time, who knows. Love the truck and so far the only thing other than regular maintenance that I have had to fix is the alternator going out.

Posted

That's because the average owner and mechanic don't know the difference between a G80 limited slip differential and an G80 mechanical locking differential. That plus the fact that GM uses the same G80 rpo code for both, which adds to the confusion. Limited slip differentials (aka Posi) are normally installed in performance cars. The only truck to ever get one (known as RPO G86) is the Quadrasteer, QS was a Dana axle. A locker was inappropriate for the QS.

 

Here is the SPID label from my 2009 CTS, note G80, Limited Slip Differential because no car gets a locker.

da8939d6-7af3-4838-a7ee-5954e36d4698_zps

 

2012 GMC pu, note G80

DSC00004.jpg

I know all that thanks lol. G86 was also used in the 9.5" 14 bolt in the Trailblazer SS as well because gm chose to give them a limited slip instead of a gov lock. There may be some 10.5" 14 bolts out there that are G86 coded from the 80's and 90s but I don't remember anymore.

 

I don't care if the average owner can't figure it out... the average owner can't handle basic maintenance. However the service departments should and yet in recent times I have still had one mention you are supposed to use additive in the gov lock... I just shook my head and left lol. On the flip side back in 2014 when I had a CTS V I had a parts monkey have a freak out on me that no vehicles built in 2010 by GM needed limited slip additive. I just told him he was an idiot and either get me the additive or I would go elsewhere because it wasn't for a gov lock in a truck.. he just turned red and got the bottles. Peoples haves the dumbs!

 

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Posted

^Exactly 1994 Vmax. I use a paint marker on the tires to indicate the proper tire rotation PER THE OWNERS MANUAL DIAGRAM for my wife's 2015 Enclave. Every single time I take it in, or she does, the service writers give us a rash of crap about not being able to change direction of tires, GM changed the rotation now. On and on and on. I just politely smile and ask them for the updated GM literature, TSB, Owner's manual revision etc and I'll be happy to oblige and agree with their back to front, front to back half-arse rotation pattern. They can never produce anything. Not to mention the Michelin website rotation pattern agrees with GM's owner's manual diagram. Just another example of them bamboozling average people who don't know or don't paint mark the tires so they know for certain it's done right. When my silverado was new and I was using the free oil changes I did the same thing, paint marked them and notified the writer. 4hrs later for an oil change and rotation on a Saturday, it comes out with the wrong rotation pattern. SMFH. DIY FTW.

Posted

^ I don't buy that BS. When a diff and gears break-in, there are lot of particles. It's "lube for life" b/c the average life of a car is probably 6yrs/100k. Life is also subjective. Who's life? What life? It's more BS from the mentality to save oil and save money and decrease their maintenance costs to fleet buyers. I had a wheel seal fail at 16k. the dealer replaced the wheel seal and re-filled the diff with non-GM fluid. It's not purple... looks like regular gear lube. I know before I took the truck in for the repair the "purple" stuff looked black as night. Since the wheel seal fluid flush repair the lube has stayed clear. Breaking in diffs requires a flush. Period.

Posted

From GM's perspective, the life of the vehicle is the length of the powertrain warranty. In my opinion it's not a coincidence that a transmission/T-case fluid change isn't required until nearly 100k miles in their maintenance schedule.

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