I found this interesting discussion about oil catch cans on a Corvette website. What grabbed my interest is a comment that strands of the steel mesh filter element may be pulled into the cylinders and, possibly, do damage. I have never heard this before. I don't think that we have much too worry about, however, because our Hemis don't create enough vacuum pressure for this to happen.

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