BMW Oil Separator crankcase vent PCV valve GENUINE Brand NEW with 1yr WARRANTY Oil Separator / Crankcase Vent pressure regulator. 528i and z3 NOTE: Fits from 09/1998 production date. Please email us your VIN to confirm fit. If your Bimmer is blowing blue smoke, this is the likely culprit. This part takes a hose from the crankcase, filters out the oil, and feeds the excess air pressure back into the intake manifold. If this part lets too much oil through, it will burn in your engine and cause blue smoke out of the exhaust. Relatively easy to replace.