Finally got around today tackling this service on my newly to me acquired Z4coupe.
I did lots of searching and people use all kinds of fluids on these manual transmission
First i my fill and drain plugs were not 17mm's
I had to use 8mm Hex bit socket for fill & drain.
I ended up using Pentosin MTF2 OE fluid. Just what the yellow sticker on the trans required. The past month i have stocked up on this stuff, because they have stop making it, second, this is the proper oil for my E46 M3's,
http://www.m3forum.net/m3forum/showthread.php?t=590024
The job took about an hour as i took my time and had a couple of beers
Took the car for a spin and
The shifting is like my Kimber Ascent bolt riffle, "crisp"
Cheers!