Rear Diff Axle Seal Leak??? And Question about Transmission Oil Change

[BMW_E53]

Originally Posted by wpoll

That diff is covered in a fine mist of diff fluid. It's not leaking out fast enough to make drips, but enough to cover the exterior of the diff, then mix with dust etc. to make a sticky coating over the whole diff body. Not sure which of the three seals (front, left and right) and causing it but at least one of them is gone. Clean down the diff, change the fluid and watch for the leak - one location will get "dirty" quicker than the rest.

Re. the transmission, the consensus is the fluid flush (100%) will likely kill the transmission. A drain and refill (with a filter change) will change about 40% of the total fluid volume. Do a second drain and refill while later and you should have mostly new fluid in service. This method reduces the chances of crap getting into the valve body, and you can change the electrical connector seal when you do the filter change.

But it may be that only a mechatronic rebuild will fix the hard shift.

Ok so the differential is spraying a fine mist of oil while the vehicle is in motion I'm guessing.....and the indy said it was the left seal is leaking so I may just have them fix it. And thank you for clarifying about the transmission oil change, sounds like I could do it myself. What do you think about the ZF atf oil? It says it is equivalent to the Shell and is $10 cheaper than BMW oil. Also how many quarts would be needed for two drain and refills?

[wpoll]

Originally Posted by BMW_E53

Ok so the differential is spraying a fine mist of oil while the vehicle is in motion I'm guessing.....and the indy said it was the left seal is leaking so I may just have them fix it. And thank you for clarifying about the transmission oil change, sounds like I could do it myself. What do you think about the ZF atf oil? It says it is equivalent to the Shell and is $10 cheaper than BMW oil. Also how many quarts would be needed for two drain and refills?

I've not done a fluid change myself - many others here have and can give better advice - but I understand it's about 4-5 litres per change.

If you have ZF 6HP26 transmission, you'll need to use ZF Lifeguard 6 fluid. There are alternatives but most folk recommend the ZF fluid.