I've been using the BMW branded standard gear oil, for about 15 years, before that I was using Castrol 80/90 gear oil.
I think if you use a quality brand oil, and change it regularly, I don't think you will have any issues later on.
One item that can cause you a little problem, if you don't already know it , is the rubber boot that covers the speedometer drive cable at the transmission.
It looses it's grip on thr drive cable, and allows water to enter the transmission.
Clasisc clue to this is a coffee with milk look , of the transmission oil when you drain it out .