AUSaxon00

I have an '06 525xi with the same differential. The #2 bolts are for holding the differential cover on. The #3 plug with O-ring is the "drain/fill" plug. To drain this differential, you need to suction out the fluid. I used the fluid pump (FP500) from Bav Auto to do it and pulled out about 1.2 liters. Motive also makes fluid extractors which, I presume, could do the job as well. I also used the pump (after cleaning) to put the new fluid into the differential. When changing the differential fluid, the TIS recommends replacing the #3 plug, which I also did ($4.95 ea @ Bav Auto). The gear oil I used was Motul Gear 300, and so far I have not had any issues.

UDM535i

I was thinking #3 is the fill plug and couldn't find the drain plug. So, I was thinking about suction. I have Mityvac fluid evacuation equipment and I'm going to use it when I change my diff oil. Thank you for your info.

lcc014

I bought mine from ECS tuning.

krusir

BMW remove/kill the drain plug because they have "lifetime" fluid. They don't want driver to have hands on it.

I too believe there is no such "lifetime" fluid. Suction method is just workaround, it don't really get all the fluid and dirt ( if there is any ) out. The flow of the fluid to the drain hole certainly help pull our dirt out. However, I don't think it is worth to open the back cover to get all fluid out. I will live with SUCK method.

I am going to buy Acura next time.

AUSaxon00

Interestingly, both the front differential and transfer case on my '06 525xi have separate drain and fill plugs, which are the identical part to the fill/drain combo plug on the rear differential. There must be some design reason for the rear differential to be constructed in this way, as opposed to BMW just trying to keep people from maintaining their car as they wish.

Because of the way the rear differential is constructed on the inside, the suction method, if practiced with some care and patience, can remove almost all the gear oil. In principle, this is not very different from a DIY transmission fluid change, where a fraction of the fluid in the torque converter cannot be easily removed. In my opinion, changing 90+% of the gear oil is better than changing none.

With regards to removing the cover of the rear differential, this is not a task to be undertaken lightly. It is not shown well in the images above, but the cover of the differential is bolted to a rear subframe cross-member. In order to remove the cover you need to remove both half-axles from the differential, drop the back part of the exhaust system, dis-assemble the drive shaft and then you can remove the securing bolt to drop the differential. Once lowered you can remove the 7 bolts securing the cover to the differential. The book time for this job is about 4 hrs for a BMW tech, which runs about $400 in labor at my local dealer. For the average DIY'er this would be a fairly involved undertaking, and probably not worth the effort to get the remaining few 10's of milliliters of gear oil out.

Rizbel

I observed the same oil condition during the Quaife unit install. The original SAF-XO oil at 60K+ miles looked better than the Redline 75W-90 at 30K miles.
I'm switching back to BMW oil for the 1,000 miles break-in oil change(then every 30K miles). Thanks Raj .


And for added protection-->
-Custom made for BMW vehicles, featuring a large 8 mm neodymium magnet rated at 300° F.
-Double-sealed for a no-leak connection
-Plug will seal and reseal repeatedly without having to replace gasket.
-Impervious to vibration and temperature variation -- won't back out when properly torqued.
-M22 x 1.5

lcc014

How many of this new plug do we use for our differential, 1 or 2 ?

Rizbel

I will only use one plug with the magnet for the drain, and a regular M22 X 1.5 (BMW part# 33117525064) for the fill hole.

lcc014

Thanks, that make sense.

sunny 2005 bmw

Great wright up I have a 2005 bmw 545 with 65k on it. I am new to bmw but have some experiance with differential oil change. I have a 99 jeep that I use amsoil 75w-140 can I use this in my 545.