Hi,

I want to do an oil change on my diff. I just ahve a few qestions.
It seems that there is no need to open up the diff to change the fluid. There is a fill and a drain plug, and that makes it quite easy, but I would liek to know if there is some sort of gasket in the diff. I change the diff oil in the locker in my chevy truck, but unfotunately it doesnt have a drain plug. In some ways this is a royal pain, because the gasket isa pain to remove, however, I can really clean inside, getting the sludge out and the metal filings off the magnet.
I am really concerned because I want to put Mobil1 into the diff, but are worried about a possible gasket. If there is no gasket, and no parts, such that it is welded, then how would one clean it, is there a magnet inside at all? If it is welded, I can use mobil1 no problem and thats that. If there is a gasket, I suppose I should use regular dino oil, unless gear oil, being 75w-90 or so is sufficiently thick and viscous that it shouldnt seep out or leak, or else change the gasket, which Id like info on, if that is the case.
Thanks very much,

JMH

Check out the picture in this thread:

Look What Mobil1 Synthetic Gear Lube Did To My Diff.

Looks like Mobil 1 will clean the inside of you diff without having to open the case. You might use Mobil 1 once as a flush for a month or so then change it with a long term fill.

Sixto
91 300SE
81 300SD

Just checking the rear end can be a pain in the rear end.
Mine we use ratchet, breaker bar, impact, and chatter gun.
It would not budge.
Got new one with cooper gasket from Mercedes.
18" breaker bar and 4' cheater pipe and 250 lb. and it finally let go.
Took old one out and with a few words of praise for the idiot that put that much pressure on it.
It should come out with a ratchet.
Good Luck
Charlie

Which warrants reiterating the cardinal rule of differential oil changes -- remove the fill plug before you remove the drain plug. Do not proceed if you can't remove the fill plug.

Sixto
91 300SE
81 300SD

I sprayed liquid wrench on my threads and it came loose with no problem. Here is the link to my original inquiry.

The proper way to put a car on all fours?