Can we agree that a K&N filter is better than no filter at all?  Of this, I am sure because each time I have cleaned or replaced my K&N, it has been noticeably dirty.

Opinions usually vary - and mine does as to the use of K&N filters in our often-IFR-used airplanes.  I use the K&N filter despite the reasons cited by previous writers on this topic.  My use of K&N filters is because they pass the "suck" test while paper filters fail this test (I have not exhaustively tested  automotive paper filters).

In the mid 1990's, I remember reading of a light aircraft that crashed because it had ingested its own wet air filter; yes it was a cellulose-type automotive filter.  (Sorry, I don't have references to this article or event.)  Still building my LNC2 at that time, I elected to do my own suck test - and I recommend that you too do a suck test on your aircraft filters.

Conduct the suck test by cutting out a piece of old paper filter (automotive) and then wet part of it by dipping it in water.  The other half should be kept dry.  Now, suck on the dry part and you will find that breathing is easy.  Next, suck on the wet part and you will find yourself turning blue for lack of oxygen.

Repeat the suck test on a K&N filter and you will note that breathing is easy whether wet or dry because the filter is oiled.

I was satisfied that a wet paper filter could, indeed, cause power loss on an aircraft engine - especially because our IFR aircraft must necessarily advance into clouds, rain, ice and snow without the slightest power hesitation or interruption - unlike racing automobiles that wisely avoid rain, ice and snow.

My shoulders are broad and my loins are girded; I can take the slings and arrows that are sure to come.  In the words of Bill O'Reilly, "Am I wrong?"