I was given a complete K&N FIPK II intake kit w/K&N filter almost 10 years ago when my Jeep was brand new. I was concerned about the long-term health of my engine after cleaning out the intake tube and noticing fine dust inside of it. So, I did a simple upgrade and an still very happy with what I have.
I kept hearing that, 'The dirtier the K&N Filter gets, the better it performs.'
Not sure what to think of this logic, I went with an AEM non-oiled conical filter for a Ram 1500 pickup, and am still very happy.