Creamy substance in coolant valleys [pic]

[maldotcom2]

I pulled my intake manifold off tonight, and two of the coolant valleys have what looks like an oil/water mix. The rear two that don't have a corresponding hole in the manifold, for whatever reason? The engine oil isn't creamy though. Any ideas?
In the pic below im referring to the top left valley. it's nearly blocked by this crap.

[VSIIBerlinaL67]

oil leaking into the cooling system, just clean as much as you can put new gaskets, flush the cooling system and change the oil and should be fine

[hako]

As above - the oil gradually seeps thru the gasket and slow builds up and hardens.