My guess is that your oil separator is clogged and needs to be replaced along with all the hoses. Either that or you need to drive the car for longer stints at higher RPMs and see if that clears out the mayo.
The mayo is more common in the CCV (oil separator) system when the weather is cold. It's an emulsion of spent emission fumes (which includes water) and oil.
Last edited by pleiades; 12-08-2012 at 01:01 PM.