I finally got around to changing the trans fluid in the e46
5hp19 steptronic like yours.. It took about 5.5 quarts when i pulled the pan and changed the filter, then drain and fill changes of 3.5 quarts each time until it was clean.
The pan and magnets were suprisingly clean but the fluid was black .. It took around 15 quarts total until the fluid came out red. When filling it the maximum fluid temp is 122F with the fill plug out and that came really quickly