I know there are other places to ask this question, but you guys are the most knowledgeable I have ever come across. So I only feel comfortable asking here.

I just changed the rear diff fluid in my XJ. It has almost 185K on the clock. I am not sure when it was changed last (I have had the truck a shade over a year) and I figured it was about due. Plus, working on the Rover has given me the confidence to tackle other things on other vehicles.

Anyway, the diff fluid was dark. Smelled terrible, as gear oil always does. When I got it into the sun, it looked sort of like the metallic chip paint that you might see on a black or blue vehicle. There were no hunks of metal, and none of the sparkles were big enough for me to focus on, the fluid was just glittery. As I was pouring it into a jug, I noticed that I could see through the stream, so it wasn't completely opaque.

How does this sound? Is it normal for old diff fluid to look sparkly? Otherwise, the gears look good, and there wasn't any crap laying in the bottom of the housing.

 

Not a good sign, you most likely have some bearing wear going on and having been a service manager for Jeep for years, I know their failure rate.
I would suggest you swith to a 75W/140 gear oil and if you don't have one install a magnetic drain plug to catch some of that floating metal.

 

Thanks for the tip Mike. It's the standard chrysler rear end (NOT the Dana) and I had been told before they're not the best in the world.

I already picked up the 75w-90 gear oil so I'll walk it back to oreilly's and exchange it.

 

Change the gear lube once a year, it is a good part of spring time maintence, and cheap insurance too.

 

yeah the "sparkly bits" are tiny metal shavings from something inside your diff... means you have some wear goin on that you may not notice till later... if you find any small chunks of metal in there do not think "i wonder how this ended up in there?" because it did not magiacally "get in there" it was always in there, just at some point attached to something else in there and now the part that used to be your gears in metal flake in your oil painting...

 

Well, I figured that, not knowing when it was changed last, there would be some sign of wear in there. I'm just glad/surprised that there was no larger hunks of metal in there. 185-190 miles I would expect it. I'm going to walk over to O'Reilly's here in a few and exchange my gear oil. I sure as hell can't driver over there, seeing as how my GF has the Pontiac, and the wiring harness on the Land Rover looks like a brain stem that's been hacked back together with electrical tape, hopes, and dreams.

 

The only 75w/140 gear oil was Royal Purple, and it was $19.00 a bottle. I stepped down to standard Castrol 85w/140 and it quieted that rear end down for sure. I don't figure it will hurt it, esp if I have some wear.