Gross gear oil @ 8k miles

[rharr]

Just a FYI for anyone that cares, was at my buddies shop helping with a regear on another friends JTR, we popped the drain and rear dif cover and what a nasty gross stinky dark mess. The oil in rear diff was coffee brown, burnt smelling, with a fair amount of metal fines on the magnets. Buddy said it looked like 80k mile oil.

This JT is just a daily driver, no towing, no abuse, so for the oil to be toast at 8k is very surprising. The good news is Jeep makes it very easy to change the oil in the diff, don't even need to pop the cover, so anyone that cares, it might be worth a hour of your time to dump the factory stuff if you haven't done it yet. That's my weekend project....

Also of note was the amount of metal filing that collected on the locker phase sensor (aka the little switch on the carrier that tells the ECU the locker is locked or unlocked) this phase switch uses a small magnet to identify its position, and if it is caked in metal it's going to screw up the signal, I suspect that is what is happing to all the folks that are having locker/4x4 error codes. It's easy enough to clean if the carrier is out of the axel and the bearing is pulled but more tricky if everything stays assembled.

To keep the filings down, a fluid replacement in the first 3k or less would seem prudent to catch all the stuff stirred up from a break in on a new jeep and maybe going full synthetic (75w-85 (GL-5) 1.5 liters). I am also thinking about getting a second magnetic drain plug and replacing my oil fill plug with it, to further help catch any metal.

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[just_another_guy]

I changed mine at 6k and didn't have any metal in the oil, just slightly darker oil in the rear diff from the limited slip. No lockers on mine though.

 

[Gren71]

Ive always wondered about this. Since I pull my camper once a month ive had it in my head that I would have mine changed sooner than later...now 57k miles later...still thinking about it

 

[rharr]

I'll report back on how my oil was after I drain it this weekend. I'm at 4500 miles now, with some utility trailer towing and 6 hour highway runs.

My JTR and the "gross" JTR were built the same month and delivered 2 weeks apart.

 

[rharr]

Here is mopars finest out of my rear diff at 4500 miles...... Coffee color and mildly burnt with some metal filing fully caking the magnet.

 

[Chilli]

I'm surprised at the color.

At 10K. on our JTR, both ends are getting changed this wknd.

Much thanks for the pix of the lube.

 

[Chilli]

Is there any issue to use brake spray cleaner to rinse out the gears, etc ?

 

[rharr]

You can use breakcleaner just keep it away from the locker sensor. I didn't bother to pull the cover I just used the drain plug. I will pull the cover in another 3k when I flush again. I suggest you do the same, just use cheap gear oil and flush again in 3k to check status. Then use good oil when the metal reduces it collision on the magnet.

Front wasn't as bad, honey color. But magnet was covered in goo.

Friend with auto 4x4 his front was more toasty.

Take pictures of your oil, I would like to get a collection going.

 

[Courtsm3]

Hmm. I should take a look, im at 25k. Uh oh.

 

[RdFx21]

I had similar results changing diff fluid two weeks ago: dark oil and metal shavings coating the magnet on the rear; honey-colored with less metal shavings, but still covering the magnet on the front. I was at ~2k miles on the odometer. I replaced with 85w-140 synthetic.

 

[Mac]

May change mine this weekend, what is the capacity?

 

[rharr]

Until it leaks out the fill hole

 

[Mac]

Until it leaks out the fill hole

I wanted to know how much to buy.

 

[rharr]

I wanted to know how much to buy.

Read the first post

 

[WXman]

Is the gasket reusable or do we need a tube of RTV to reinstall the cover?

These axles are notorious for going through fluid. I think they are crap axles honestly. Bearing issues, flange seal leaks, etc.

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