BMW used Pentosin CHF11s and ATF. They are not compatible. The caps are marked. As long as it says ATF, you can use any ATF. The differences in ATFs (Dexron, Mercon, etc) are for the clutches in the automatic, and none of that matters in a PS system. Use any clean fresh ATF. I would use a Dexron just because it is easy to find.

You can use the turkey baster to change the reservoir fluid, but I am not a fan of that. You don't get the old fluid out of the steering gear at the bottom, and that is where all the crap collects. I would take off a return line. It is messier. If you want to use the turkey baster method, do it sufficient times to get the fluid mostly changed, with lock to lock cycling to move the old fluid along.

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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