I am having a hard time changing the differential fluid in my 92 525i. All the diy's and parts people say the drain and fill plugs are 10mm allen key bolts however mine diffinately are not. The closest I have come is a 17mm allen key which is a little to big and the next standard size down is a 14mm( The parts supplier Napa orders from only make 11mm,12mm,14mm,17mm,19mm in oversized allen wrenches). I know I can special order a 16mm but after searching all the usually parts suppliers I use pelican parts, bav auto, oem bimmer parts they all claim the proper tool should be a 10mm allen wrench which confuses me a little.:dunno: Anyways my question is since I'm sure someone on here has successfully changed the differential fluid for an e34 sedan (m50 engine, standard trans, I would list the differential but the tag is so dirty I can't read it) I was wondering if anyone had any advise or has gone through this before and knows the solution before I spend $20 on a part I'm not sure will work. thanks for any help you guys can offer.