Originally Posted by SEMA Guy

What the Porsche Dealer told me (after listening to several cars and consulting their PCNA Tech Rep) was that GT3's operate at a near vacuum in the crankcase (this added 10 HP). When the car is shut down, the outside air pressure and the vacuum seek to equalize. As this equalization occurs, it displaces some oil which is the gurgling sound we all seem to hear. Makes sense if you remember high school Physics class.