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2016 Rear Differential Fluid/Rear Axle Fluid

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Yes the 2014+ Diff cover gasket is reusable. I coated mine with a thin coat of blk RTV silicone for insurance. Clean the axle gasket surface very well.


I did a PML diff cover for slightly extra capacity and more importantly.... drain plug with magnet.



Make sure you clean the magnet mounted inside the axle housing under the gears. Lots of crud that thing caught. I spent a lot of time cleaning that thing up.


Some trucks to have LSD's. I had a '07 F250 FX4 which used a clutch style LSD in the rear Sterling 10.xx" axle. Ford fluid had the proper FM pre-added. The proper info should be stated as GM does not offer a clutch style LSD. GM offers open one wheel peels or a G80 locker. Which according to EATON directly, no FM at all should be in the fluid as it affects the G80's performance. They specifically told me on the phone the M1 75/90 had FM therefore they did not recommend it. This is simple. 75/90 Full Syn, API-GL5, no FM of any kind.


Simple, intuitive post! Thanks!

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  • 4 weeks later...
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I am running 75W-90 Full syn GL-5 gear oil with no friction modifier in the front and rear diffs. If you have a G80, make sure you have no FM!!! That BS about 75/85 is for CAFE. And thenin the front they run dino 80-90 for cost cutting.... just run a quality GL-5 FULL SYN 75/90 in both diffs.

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I just got my G2 Rear Diff cover and it's pretty beefy! Looks like it will add almost 2qts to fill and has dip stick with magnet and drain plug with magnet plus a temp sensor hole if needed. I put in 75W-90 AMSOIL NO FM just like what FL335i is screaming and it's pretty good stuff. Problem is I ordered it months ago when I changed my rear fluid and now it showed up on doorstep? I don't have much ambition now that it's 110f daily.........

Edited by mookdoc6
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  • 3 weeks later...

I am running 75W-90 Full syn GL-5 gear oil with no friction modifier in the front and rear diffs. If you have a G80, make sure you have no FM!!! That BS about 75/85 is for CAFE. And thenin the front they run dino 80-90 for cost cutting.... just run a quality GL-5 FULL SYN 75/90 in both diffs.


This is available local to me and they have 5 qts in stock locally. Carquest branded, produced by Old World Industries (they make PEAK stuff). Its a fully synthetic, meets GL-5, no additives. Thoughts?

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  • 10 months later...

So to confirm 75/90 Full Syn, API-GL5, no FM of any kind is the correct fluid for both front & rear diffs (including the locker rear diffs?) i.e. a Redline GL-5 Gear Oil 


What are the torque specs for the rear diff cover and the drain/fill plugs for the front diff?



Also on a semi-related note what fluid & quantity should be used for the t-case? And what are the torque specs for the drain & fill bolts? 

Edited by 94boosted
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  • 2 months later...

Hey I want to thank everyone in this post. It answered all my questions that I had!!


I am towing alot with my truck. Of the 53k on it 20k is towing 10000 lbs. Been over the continental divide 2 times and over the rockies on various camping trips. I expect it to haul that trailer no matter what the hill or terrain in low range if need be 5k rpm in first gear to climb up and out of a place I should not have been and it did it. Every time it never fails. So the point being, the fluids have been in server service and I thought my fluid history might tell something about the truck and how the stock stuff performs under top load conditions. My last truck was a 06 LBZ banks 6 gun chip. So I am comparing the two trucks all the time. And the 06 was a work truck for 340000 km. very reliable truck never let me down either. My 16 6.2L max trailering\towing 1500 has been through a lot. I rolled it in the forest in feb of 17 and did 35,000$ of damage and insurance fixed it.All body damage on like every side(42 days of labor) no kidding 42 DAYS of labor to fix it. Got it back from that tragedy and carried on like normal towed my big ass trailer all over the place.t The rest of the km the truck is empty. So this is what I found at 30 45 and 50,000KM




 My front diff fluid was white at 45k when I changed it fo the first time. It was not running out of the fill hole because I pulled that first so I am relieved to know it was pattern goo. It felt smooth and smelled ok.I changed it with AMSOIL severe gear 75W-90. I filled it till it came out the fill hole. 


I changed my rear at 30k and it looked dark and not at the fill plug level. Didn't smell burnt but I bet it got pretty hot going up some of those hills in Montana and Idaho, and washington. I should have changed it earlier. I Changed it again at 50k and the level was good the color was a little dark like it picked up the rest of the contamination that was in there.Any way good color and it only had 20k on it but 7k were pulling the trailer. I didn't pull the cover either time. I pumped out with a dip tube I put in the fill hole and a pump. I changed it both times with AMSOIL Severe Gear 75w-90. I filled it to the fill hole which is like 2.6l like the spec is maybe a bit more. Zero issues with the diff. Locker works fine. I am considering putting this diff cover on. Any feedback? I ordered a temp gauge too.





Transfer Case 


Changed at 45k. Came out darker than I would like to see but full and redish. The magnet on the plug had a huge pile of crap on it. Nothing hard or fragment of anything just a big prickly looking pile of what came out from inside of my transfer case. I filled it with AMSOIL ATF Signature Series and short changed it 2 weeks later and there was nothing on the magnet and the oil came out brite red. It's only a couple liters. Peace of mind for me.




I made my own dip tube just for the trany plug hole to syphon out whatever is no the pan. I got 6.5 liters out.It was darker than I would like and it was due for a change. I did the same thing again 2 weeks later after a few hundred km.  I am going to do this every 20k from now on and see what it looks like next time. I noticed a difference in the shifts right away. I didn't expect that. It seems to work better on AMSOIL.


If you made it this far. Thank you for reading. 

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