1993audi90

Pulled valve covers (95 audi 90) to replace leaking gaskets. There is a screen or mesh filter? near the rear exit lines in the valve covers. I suppose these exit lines are part of the PCV system, as the hoses that attach to the valve cover go to the throttle body. I think the screens or mesh is supposed to keep oil from going to the throttle body.
Are these filters or whatever they are called replaceable or cleanable? I've got major sludge buildup inside the covers, Major mess.
The passages are open I can blow into the valve cover from the outside. I've never had a car with this much sludge in the valve covers. I change oil regularly. What is this all about?

Lago Blue

Welcome to undocumented but required maintenance.

Are they cleanable? Sort of, however they are riveted in place. VAP did a write-up on these. Some have removed the rivets and had better success at cleaning them, but that requires you be prepared to tap the holes for re-attachment. I did it. IIRC the OEM ones are a welded assembly of stacked stainless-steel screens. I installed a heavy mesh cover and filled behind it with stainless-steel pot-scrubber pads.

I think this stuff is an oil/water mixture. Especially prevalent in cold weather.