I'm into my 4th year with a wix air filter.
in December I'll pull it out & see if I should replace it or not.
Gas mileage hasn't been sacrificed, the engine purrs, oil stays clean (thanks to PPU oil).
I might replace it just because I'm not out to set an air filter longevity record!
I'm going to be removing my k&n from my Ranger pickup since 1997.
After reading from Wix's training tutorials, once a paper filter gets "coked", it will flow as much air as a k&n style filter.
AND it'll trap the dirt that the k&n lets thru. So maybe 300 miles and the paper filter in theory flow a good amount of air.
I'm ok with it.. tired of seeing my fresh oil get dirty in 500 miles.