i was helping somebody change their oil last week and noticed yellow colored clumps in the oil filler cap and around the oil filler opening.

is that sludge? if it is, can i do anything about it besides recommend that they have their oil changed more frequently?

 

I would change the PCV valve for starters and see if that clears it.. Volkswagons do this a lot and I dont really know why, other than a leaking head gasket