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Duramax Rear Differential 12,000 on fluid/25,000 total miles #5267287 11/14/19 03:58 PM
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wwillson Offline OP
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This is a 50/50 mix of SuperTech 75w-90/75w-140 run for 12,000 miles mostly pulling the truck has a total of 25,000 miles.




Capture2.PNG
Re: Duramax Rear Differential 12,000 on fluid/25,000 total miles [Re: wwillson] #5267401 11/14/19 05:56 PM
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JohnnyJohnson Offline
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I'm not used to looking at UOA for Rear Differentials. But that FE seems really high to me? Am I wrong? Was the Lubricant very discolored? Its been 20,000 miles plus for my Duramax now. I was thinking next summer to get it done. Did you use OEM Lube or something else?

Last edited by JohnnyJohnson; 11/14/19 05:57 PM.

2004 Corolla 137331
Out: Havoline Pro DS 10w-30 Purolator PureOne 10-29-19 136457
In: Pennzoil Platinum HM 5W-20 ST 4386
2006 Duramax 76862
Out: T6 5W-40 XG9100 73705
In: Rotella Dino PH9100 11-3-19
Re: Duramax Rear Differential 12,000 on fluid/25,000 total miles [Re: wwillson] #5267412 11/14/19 06:05 PM
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The teeth of hypoid gears experience more sliding wear than many other gear designs. I would expect Fe content to be high.

Re: Duramax Rear Differential 12,000 on fluid/25,000 total miles [Re: wwillson] #5267433 11/14/19 06:29 PM
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Originally Posted by wwillson
This is a 50/50 mix of SuperTech 75w-90/75w-140 run for 12,000 miles mostly pulling the truck has a total of 25,000 miles.

Are you staying with 12k OCI or extending further?

Re: Duramax Rear Differential 12,000 on fluid/25,000 total miles [Re: wwillson] #5267455 11/14/19 06:48 PM
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I'm all in on the early drain and fill. What do you plan on for the next drain fill? Meaning mileage? I did my F150 at 25k and will do it again at 100k. Just wondering what you plan. I also did my Subaru at 30k and will do again at 100k. And then again at 200k and then never again til she is put down.


2015 F150 Lariat M1 5-30 EP FRAM Ultra(40k)
2017 Sub OB M1 5-30 EP FRAM Ultra(67k)


Re: Duramax Rear Differential 12,000 on fluid/25,000 total miles [Re: wwillson] #5267661 11/14/19 10:13 PM
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wwillson Offline OP
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Biscut,

I will probably go to 25,000 for the next interval. Does anyone know what GM recommends? I can't find it in my manuals.

Re: Duramax Rear Differential 12,000 on fluid/25,000 total miles [Re: wwillson] #5267682 11/14/19 10:46 PM
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A quality 75W90 (we use Chevron Delo stuff) will easily go 500,000 miles in a AAM or Dana rear axle on a GM. We do it, and have had ZERO failures. We dump the factory oil at the first service (usually around 10k miles) it's usually kinda nasty, and put in the Chevron and forget about it.


HDEO in Diesel Engines. No spark plugs here.
Re: Duramax Rear Differential 12,000 on fluid/25,000 total miles [Re: wwillson] #5267724 11/15/19 12:39 AM
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I was always recommended M1 75W90 in my gm’s. I used RP Max-Gear 75W90 in my Express 2500HD van. That diff was smooth as butter along with being as quiet as a mouse. I realized the highest fuel economy with RP products also.


2008 Jeep Patriot Sport FWD 2.4L 246K QSUD 5w20 Fram UG

2000 Ford Expedition AWD 4.6L Cleveland 298K STech FS HM 5W30 FL-820S

1998 Dodge Grand Caravan FWD 3.8L V-6 163K Car Heaven

Re: Duramax Rear Differential 12,000 on fluid/25,000 total miles [Re: JohnnyJohnson] #5267808 11/15/19 06:34 AM
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2015_PSD Offline
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Originally Posted by JohnnyJohnson
I'm not used to looking at UOA for Rear Differentials. But that FE seems really high to me? Am I wrong?
No, it is not high. My 2015 F250 had 339PPM of FE with only 8,600 miles on the first OC. The vast majority of axle wear occurs in the first 15,000 miles or so and despite longer and longer runs the wear metals will continue to drop.


2019 o)|||||(o Rubicon Wrangler Unlimited 3.6L V6 [Castrol Edge 0W-20 + FRAM Ultra]
2018 Mercedes Benz C300 2.0L Turbo [Pennzoil Platinum Euro 0W-40 & Mann filter]
Re: Duramax Rear Differential 12,000 on fluid/25,000 total miles [Re: 2015_PSD] #5267817 11/15/19 06:57 AM
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4WD Offline
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Yep
First 17k of 2017 Tahoe

D7BBE443-92A4-4032-8B6B-19CD53200CB3.jpeg
Re: Duramax Rear Differential 12,000 on fluid/25,000 total miles [Re: wwillson] #5267834 11/15/19 07:33 AM
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Originally Posted by wwillson
Biscut,

I will probably go to 25,000 for the next interval. Does anyone know what GM recommends? I can't find it in my manuals.


You won’t like this Dubya.

From the 2018 Duramax Supplemental manual it does not suggest a differential oil change, at least not in the first 150,000 miles. Same for the 2020 Silverado manual.

From my 2008 owners manual on my 3/4 ton Chev, it does not suggest differential fluid change as well. I did one at 100,000 miles using AC Delco 75W90 Synthetic and another at 175,000 miles using Motomaster 75w90 Synthetic.
It runs perfectly with 180,000 miles on it.

For the transfer case it suggests 50,000 miles but I do it every two years. It’s as easy as an oil change.


YRMV. smile

Last edited by Snagglefoot; 11/15/19 07:58 AM.

If you want the job done right......do it yourself.
Re: Duramax Rear Differential 12,000 on fluid/25,000 total miles [Re: wwillson] #5267874 11/15/19 08:10 AM
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AC Delco 75W90 Synthetic after 75,000 miles with some towing. 10-3/4 inch 14 bolt in a Chev 3/4 ton with 175,000 miles. smile

0319B048-9388-416A-8D17-C15A56A38FD9.jpeg
Last edited by Snagglefoot; 11/15/19 08:12 AM.

If you want the job done right......do it yourself.
Re: Duramax Rear Differential 12,000 on fluid/25,000 total miles [Re: Snagglefoot] #5267876 11/15/19 08:10 AM
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4WD Offline
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Same here … AAM builds the axle and there is nothing in my manuals …
Just thinking 50k still works after an early change

Last edited by 4WD; 11/15/19 08:11 AM.
Re: Duramax Rear Differential 12,000 on fluid/25,000 total miles [Re: wwillson] #5268237 11/15/19 02:34 PM
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userfriendly Offline
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I find that GM under fills their differentials in my opinion. I like about 1.5 inches below the fill hole. I'm slowly switching everything to 80W140 Chevron & Petro-Canada.

Re: Duramax Rear Differential 12,000 on fluid/25,000 total miles [Re: userfriendly] #5268306 11/15/19 03:43 PM
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Originally Posted by userfriendly
I find that GM under fills their differentials in my opinion. I like about 1.5 inches below the fill hole. I'm slowly switching everything to 80W140 Chevron & Petro-Canada.

Spec is 17-21 mm (0.6-0.8 inches) below fill hole.

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