Since you have the ZF tranny I believe the original fluid was the Shell 1375.4. My 2007 335i has the same and when I did the fluid/pan change at 60K miles it didn't stink. It was dark not red and the new shell 1375.4 that I put back in was amber colored and had little smell. It took about 6 liters to refill. Now I am at 95K and everything has been working perfectly but recently my mechatronic sleeve started leaking. I hear that is a common issue.
94 318I (Daughter's car), 96 740IL(current project), 97 528I(DD), 07 335I(Son's car)