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Just a friendly reminder to change out your factory transfer case fluid sooner than later. Picture below is my drain plug magnet at only 27,000 miles on my 2019 Chevy. Usually try to do this within the first 10,000 miles, but unable to dedicate the time until the recent Holidays.
 

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My dads 2016 LML with the first change at 46k miles. The fluid was starting to get dark brown.

My 2017 L5P at ~16k miles/ 730 engine hours. The fluid was still cherry red but had visible metal in the fluid.

I also changed the spin-on trans filter at the same time, the filter media was getting pretty loaded. The transmission filter magnet had some fuzz on it but didn’t look terrible.


I haven’t changed my front and rear diffs yet, but plan to soon. I think getting the break-in wear out early is important.
 

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Discussion Starter #4
My dads 2016 LML with the first change at 46k miles. The fluid was starting to get dark brown.

My 2017 L5P at ~16k miles/ 730 engine hours. The fluid was still cherry red but had visible metal in the fluid.

I also changed the spin-on trans filter at the same time, the filter media was getting pretty loaded. The transmission filter magnet had some fuzz on it but didn’t look terrible.


I haven’t changed my front and rear diffs yet, but plan to soon. I think getting the break-in wear out early is important.
We think alike.

I did my transfer case, outer transmission filter (2nd time), front & rear differentials, fuel filter (3rd time), and an oil change all at the same time ... about 4 hours in our home garage on my back.

Rear diff was already getting fairly black ... so it was ready to be changed. Front was still caramel-colored and probably did not need to be changed. However, I changed both diff’s so they have the same fluid. Mobil Delvac 75W-90 was available at a great price thru Summit.

Only thing left is the tranny fluid and the internal tranny filter. Not looking forward to this project ... I always make a big mess on this one ... especially in a home garage on my back.
 

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UT,
What fluid did you use in your xfer case? The 75w-90? Just wondering as my 4500 shows a synthetic 50W in the xfer and the 75W-90 synthetic in both diffs.
I just hit 10K on the truck so after seeing your pics-- off to the store to find some fluid. Thanks for the post
 

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UT,
What fluid did you use in your xfer case? The 75w-90? Just wondering as my 4500 shows a synthetic 50W in the xfer and the 75W-90 synthetic in both diffs.
I just hit 10K on the truck so after seeing your pics-- off to the store to find some fluid. Thanks for the post
Book calls for

DEX VI ATF in the transfer case
75W-90 synthetic in the front and rear diff.
 

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Just changed the fluid in the transfer case and rear diff. @ 10786 on the 4500HD. I used Delvac 50W synthetic in the T-case and Delvac 75W-90 synthetic in the rear diff.OM calls out these weights and synthetics for all 3 gearsets. Going to use the same in the front when I can get the truck away from the wife. I did find a gray paste on the T-case drain plug but no flakes etc. On the rear I did find one flake and very light gray paste.
 

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Discussion Starter #9
UT,
What fluid did you use in your xfer case? The 75w-90? Just wondering as my 4500 shows a synthetic 50W in the xfer and the 75W-90 synthetic in both diffs.
I just hit 10K on the truck so after seeing your pics-- off to the store to find some fluid. Thanks for the post
Sorry for the delayed response.

Mobil Delvac 75W-90 fully synthetic in the front and rear diffs.

Mobil Dexron VI ATF (synthetic blend) in the transfer case ... plan to change it every 25k anyway.

Side Note: Mobil Dexron VI ATF synthetic blend is designed to meet the stringent service fill requirements of GM’s DEXRON-VI specification. Mobil DEXRON-VI ATF provides limited warranty protection for 2006 and newer GM vehicles.
 

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Just did my transfer case yesterday because of this thread. Mine was just as bad as the original posts. Changed my fluid to AMSOIL ATF. Just an observation from my point, get the normal quart bottles with quart bottle pump.... not a lot of room by the fill bolt for the easy fill bags from AMSOIL.


Sent from my iPhone using Tapatalk
 

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Just hit 12,000 miles. Read this thread and changed oil in my T-case, the plug looked just like everyone else's. I used Valvoline synthetic DEX VI ATF. While I was under there I changed both differentials, they looked good. Filled with AMSOIL 75W90 Severe Gear.
 

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