Every weekend I'm trying tp pick up some deferred maintenance items in preparation for the world returning to to normal at some unknown point in the future. Today it was changing the differential fluid. I used Redline 75W-90 NS, which is fine for the open diff that the E46 has. I used my trusty old pump and the process is straight-forward. I do find that I also hate the smell of heavy oils such as these, and that it's impossible to get all the oil out of the pump, so I just wiped it off and plopped it in a ziploc bag. One pointer that I've read for this style of BMW differential - Make sure the fill plug will break loose before opening the drain plug and draining the fluid. You do not want to be stuck without the ability to get fluid back into the diff in the event that you cannot get the fill plug broken free. For me it was an easy breaker bar pull and the plugs were loose, but if you have trouble, don't leave yourself worse off than you were.
