Rear Differential Fluid

HeySkippyDog · April 7, 2019

I will say that the metal was confined to the plug, but the fluid drained out was dark in color and did not smell like it was burned.

Sent from my SAMSUNG-SM-J727A using Tapatalk

TXGREEK · April 7, 2019

I will say that the metal was confined to the plug, but the fluid drained out was dark in color and did not smell like it was burned.

Sent from my SAMSUNG-SM-J727A using Tapatalk

Correct but, it did stink lol

Sent from above

HeySkippyDog · April 7, 2019

Correct but, it did stink lol

Sent from above

No, no real stink. Just smelled like oil.

Sent from my SAMSUNG-SM-J727A using Tapatalk

TXGREEK · April 7, 2019

No, no real stink. Just smelled like oil.

Sent from my SAMSUNG-SM-J727A using Tapatalk

Ok, strong oil scent though, you should look at Rear Diff covers too

Sent from above

CombsL83 · April 7, 2019

I bought my 2016 with 30,000 miles. Changed the diff and tcase fluids July 2018 with 42,000 miles. I figure I'll change it again at 75,000 miles. Have 51,000 miles now. Going to do the transmission this summer. I only use Amsoil fluids. They have a warehouse an hour from me so I go pick it up when I order it.

HeySkippyDog · April 7, 2019

Ok, strong oil scent though, you should look at Rear Diff covers too

Sent from above

I think I'll look for one with a drain plug!

Sent from my SAMSUNG-SM-J727A using Tapatalk

TXGREEK · April 7, 2019

I think I'll look for one with a drain plug!

Sent from my SAMSUNG-SM-J727A using Tapatalk

It’s got a large drain with a large magnet

Sent from above

TXGREEK · April 7, 2019

Btw, this diff cover is for my 2018 GMC 1500 6.2 with a 323 rear end.

Sent from above

Grumpy Bear · April 7, 2019

11 hours ago, HeySkippyDog said:

It was not milky, it came out darkened.

Sent from my SAMSUNG-SM-J727A using Tapatalk

That darkening is the phosphate coating on the OEM gear set. Normal. It's a wear coat they use to aid break-in.

kennerz · April 7, 2019

51 minutes ago, Grumpy Bear said:

That darkening is the phosphate coating on the OEM gear set. Normal. It's a wear coat they use to aid break-in.

This thread is kinda funny - I just did this yesterday. (front, rear diffs and transfer case) My front diff was milky and did smell, creamy/grease-like covering over the plug. Easy change.

Used the 75~90 severe gear front and back and the amsoil trans fluid for the T-case. The transfer case fluid was darker but not bad (better than expected) and the rear diff was much cleaner than I expected (57k mi) with not much buildup anywhere and still translucent but smelled like crap, but nothing smelled burnt. Just chemical, synthetic grease, type smell with a little porta potty thrown in.

Hardest part was filing the t-case cause the pump I had was kind lame. Brand new from autozone. Had a micro crack in it and was misting out the side chamber straight out of the box.

Grumpy Bear · April 7, 2019

4 hours ago, kennerz said:

My front diff was milky and did smell, creamy/grease-like covering over the plug. Easy change.

That's moisture from the air. If the gear oil does not get above the dew point on a routine basis OR the case vent is plugged or the hose is missing, disconnected, driven under water it will do this.

kennerz · April 7, 2019

19 minutes ago, Grumpy Bear said:

That's moisture from the air. If the gear oil does not get above the dew point on a routine basis OR the case vent is plugged or the hose is missing, disconnected, driven under water it will do this.

Thanks for the heads up Grumpy, I'll take a look. Does anyone know what the vent routing is supposed to look like? Need to know what I'm checking for.

Paintor · April 9, 2019

Back in the old days of non synthetic oil if your rear axle leaked the oil spot would stay there forever.

At about 10,000 miles I noticed the rear axle was leaking on the drivers side from that wire sensor going into the axle tube. Oil was all over the tube and leaving drops on the parking spot.

At about 20,000 when I had it at GM for service told them where it was leaking. Dealer said no oil leak found. By God that synthetic gear oil did wash off. They didnt check the oil level. Its 2” below the check and I could care less.

Warranty runs out this year and trading it in this summer. Synthetic Gear oil is easily washed off with mere rain water as you drive. Who knew?

New truck won’t be using synthetic gear oil in its axle.

Darksky · April 13, 2019

My front diff from the factory had a greenish creamy looking lube. I checked it when it was new. I was surprised and made the dealer show me the fluid from finger dip in another one that was up on the rack. It was the same. They said it was just how the synthetic lube in those diffs looks, from the factory.

Paintor, you’re suggesting that because of its ease of rinse off, that it is inferior? Or that it will fail if any water is able to intrude?