I installed a pair of riddler diff covers over the past two weekends.

I was really surprised how black the gear oil was. No foul smell or contamination, just pretty worn for under 4000 miles on the oil!

There was a fair amount of breakin sludge formed by shavings stuck to the drain plug. No chunks, just that greasy graphite looking stuff from very fine wear on the gears. Probably a good idea to change the fluid after a few thousand miles anyway.

Replaced the stock stuff with Mobil 1 75 90 pure synthetic.

Given the state of the oil in the diffs I think I will change out the transfer case fluid next.

 

Mine were the same, the back much darker than the front. The drain plug is magnetic, which is why it catches so much crud (a good thing). I went with Mobile 1 synth as well.

 

same with mine, only i switched to the valvoline synth. the change definitely made things smoother/quieter and about 1-2 mpg gains!

 

Same here, but I went with Royal Purple.

 

I changed mine at 15000 miles with a couple of runs in the mud. Definitly glad I went to Mobile 1. I'll wait till next scheduled service to see how its holding up. Haven't been on a trail for awhile so it probably won't be bad.

 

Is there a gasket that needs to be changed on the diff drain bolt? Something similar to an engine oil drain plug? Do you have to add anything to the treads of the drain bolt before re installing? What prevents leaks from the drain bolt after re installation?
i apologize in advance for any stupid questions. I've just never changed differential fluid before.

 

There is no gasket for the drain bolt. I am pretty sure they use the pipe thread approach. It did appear that there was something on the plug like a thread sealant from the factory.

On the front diff I wrapped the drain plug with a couple of wraps of teflon tape. Just because I had it handy.

I did nothing on the rear diff and its holding just fine. I put 800 miles on it in about 10 days and not a leak or a weep anywhere.

If you take a kitchen sponge with a scotch brite pad on one side it is easy to get all of the old gasket material off the face of the diff. Trying to scrape it off with a putty knife is a PITA. After a squirt or two of brake parts cleaner it didn't take much elbow grease to get it shiney clean. My front diff did have a small gouge where it raised a small 1/4 inch spot. I dressed that with a file to get it flat again. Probably a manufacturing oops.

One other thing is that the bell will hold a bit of brake parts cleaner. I cleaned up my sponge and soaked it all up. It will evaporate right off with one warming up but I like to get things clean and dry. I did wait about an hour after I mounted the diff cover to let the gasket material set up. Then I filled it with the right amount of gear oil.

 

Are you saying you removed the entire diff cover?
Thats not necessary is it? So if I just remove the diff drain bolt, Teflon tape should do the trick then?

 

It's not necessary just to change out the fluid. But, some people like to take a look at the gears and of course the possibility that the poster was switching out the covers.

 

I didn't use anything to re-seal my drain plugs, not a drop has leaked from them. I guess you could use something if you think it's necessary, but it probably isn't. The drain and re-fill is adequate, but many pull the covers and totally clean out the inside, which is more thorough, but because the drain plugs are magnetic it should pull any metal shavings to them anyways. If you had aftermarket gears it probably woud be smart to inspect them though.