Agree that it doesn't sound like a fluid issue. You say you have CPO until 2011, so it sounds like you need to book an appointment at your dealer, and perhaps arrange a test drive with the service manager or service advisor when you drop it off, so that you have the best chance of demonstrating the problem to them.

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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