There are pages and pages of info on here about the CCV, maybe have a look at some of that to start. Short trips can be a problem even with the CCV working. CCV stands for CLOSED Crankcase Ventilation so no fresh air gets brought in to help carry away moisture, plus the cyclone is more efficient at keeping the moisture in than it is for the oil.

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1988 325is (purchased new) sold
2004 X5 3.0 2005 X3 2.5
2008 X5 3.0 (new to me)