and to use NEO Synthetic RHD 75/90 if possible. At the very least, an API rated GL5 gear oil should be used. I use Valvoline Synpower 75/90.
I just changed my gear oil and found a very small amount of metal stuck to the magnetic drain plug... I expected to see more since everything was new from the start. The first drive I took with it, the transmission was noticeably hotter than the OE one had ever been - but that's just a function of all the gears bedding in. I let it cool over-night and the next day it radiated much less heat into the cabin.