Read this recently.
Important stuff begins on pg. 4.
Take it for what it's worth!

http://www.conceptualpolymer.com/PCV...oval%20102.pdf

"The bottom line is that most catch cans that have filter media will catch "some" oil. Unfortunately, due to the size of the media strand cross sectional diameter, a good percentage of oil droplets will pass by the media and end up in your intake. In addition, many catch cans route the blowby gasses in such a way that oil re-enters the flow stream after the air is filtered - just the opposite of the ideal direction as published by oil mist separator experts. In other words, don't route filtered gasses past sloshing oil. Some of the more expensive versions have steel wool mesh inside. Important note: After researching and receiving samples of many types of filter media, I have come to the conclusion that most woven and non-woven stainless steel and even non-metallic filter media formed as a mesh pad contains loose strands of this media. Unless a very fine strainer-type filter is used downstream of the filter media container, some of that media may be pulled into the intake of the engine. Damage to its cylinder walls may occur!"