BMW transmission and diff fluid

[carrera79]

I picked up a 2000 323ci with a manual transmission, and according to BMW the transmission and diff are filled with lifetime fluid

I've got some royal purple 75-90 and synchromax for the transmission. Good choices??? I thought I would double check here.

 

[unDummy]

It depends on what is required which is?

If the rearend is filled with any 90wt, the RP Maxgear is a good choice. If the rearend is LSD, you might need a dose of LSD additive.

If the transmission is filled with gear oil, Synchromax is a bad choice.

If the transmission is fill with ATF, Synchromax is a good choice.

 

[carrera79]

Sorry, transmission fluid is supposedly similar to atf. The diff is open.

 

[Alan]

Synchromax is a good choice for the transmission and pick whatever 75W90 you like for the diff.

 

[Quattro Pete]

carrera79, check out one of these older threads on a similar subject:
http://theoildrop.server101.com/forums/showflat.php?Cat=0&Board=UBB16&Number=515960

There is actually quite a few similar discussions in the archives. Personally, I am leaning towards the RP Synchromax as well, whenever I get around to replacing mine. I'm at 35K miles right now, still on the factory fluid.