Just found this on another site. Thanks PawPaw.

It shows the different constructions of oil filters. One big note. The K&N filter is so cheap, it DOES NOT EVEN HAVE AN ANTI-DRAIN BACK VALVE.

http://www.bullittarchive.com/5000/5...arison_Kit.pdf

 

Any idea what the date is on that? Last I knew, the K&N filter was exactly the same as the Mobil 1 filter except for the nut welded on the end. With the price of a K&N, I doubt it doesn't even have an anti-drainback valve, I question the accuracy of that page.

EDIT: I think I see what the story is:

http://www.knfilters.com/oilfilter.htm

They took a white "Premium" filter apart - the black "Pro" must be the Mobil 1 clone.