The brass usually relates to worn synchros, which are in a transmission.

Orange coloured fluid most likely means someone put orange fluid in there last time. I don't know what the official colour spec requirement is for 75w-90, but no doubt smaller oil companies could add orange, red, or purple dye in it, depending on what colour is part of their brand name and marketing strategy.

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue