Differential Drain/Fill

[zman-95-540i]

Well, I finally got the freaking fill & drain plugs out. Not fun. Anyway, there was no sealing washer on the drain plug. I'm assuming this is a mistake. Now, where to buy these washers? Can I expect to find them at Autozone or should I just head over to the dealer?

[Chris'91'525i]

I just got 2 from the dealer, could not find them at the parts stores.
My 525i's Diff. uses 2, 22 by 27 mm aluminum seal rings.
Check realoem.com to get correct size for your 540i, probably the same, but I would double check.

[ericcamaro]

Just did mine yesterday too. Along with the trans. I put redling in both and put a full synthetic in the engine too. I found exactally what you did. A washer on the Fill plug but nothing on the drain plug. I just put it back the way I took it apart. How did you get those plugs out????? I ended up making a tool. I welded a 14mm bolt to a heavy steel rod and still had to pound on it to bread those puppies lose. IM glad they didnt use those on the tranny too. Rear end took me 3 hrs and the trans took me 30 mins. What a difference a drain plug makes. Anyways mine has no washer and is not leaking, it better not be with how expensive that redline oil is.

[e34musician]

Is aluminium washer hard to find? I will get to do the diff fluid this weekend. What oil grade did you use? How much oil you can fill in?

[ericcamaro]

Go with the redline or royal purple oil for the diff. Its expensive but you only need 2 quarts so its no big deal. I went with the 75-140NS but that is because I have a open diff, if you got posi you need the regular 75-140. I hope you got the right tool for this job or it wont be fun. and dont forget to level the car or just make sure the diff is level. My car is on a slope so I had to jack the rear up quite far. good luck!!

[zman-95-540i]

I also used Redline (for LSD). I sawed off about 1" of a 14MM allen key. Stuck this in the fill plug and used an open wrench to turn it. I finally got it off by hitting it with a 3" hammer. Not easy. I spent over an hour trying to get it off using torque and it wouldn't budge.

Fill plug I used the allen key section but a ratchet fit over it. It came off pretty easy.

I'm planning to go to the dealer to get the washers today.