I'll just leave this here:https://nicoclub.com/archives/kn-vs-oem-filter.html
https://nicoclub.com/archives/kn-vs-oem-filter.html
The mentioned a... “myth” that oiled media filters actually “work better” as they get dirtier.
I've never heard of that myth, ever. Has anyone else?
And I know a little bit about this. Back when I was a Yamaha service manager, all the ATV's used foam air filters. From the factory (and out of the package as a replacement) the foam is dry. I'd have to pour Yamaha Air Filter Oil on them, saturate the foam, then squish out the excess. (and that stuff is GOOOOOEY, AND STICKKKKKKKY as hell).
The science was that the foam has much larger passages than a paper filter so they won't clog as fast, The pores weren't for physically blocking airborne debris, it was just channels with a lot of lateral surface area covered in sticky. They way the air could flow though large passages and the dirt would physically stick to the walls. The trick is to clean and re-oil the filter before it gets fully coated.
So that 'myth' runs contrary to obvious observation.
The other benefit to an oiled filter in that environment was water intrusion. In that case the water is repelled by the oil and the foam isn't compromised by water like a paper filter would be.
That was K&N's original selling point AFAIK. They had reusable cotton gauze with large pores that you oiled. So, according to them, you got very little pressure drop, why still being able to filter like a restrictive unit due to the oil. (and they get to sell re-oil kits).
What I always found funny was they used to really harp on that 1,000,000 mile warranty, but if you read the fine print, they said to replace the filter after something like 5 cleanings due to the micro fine hairs on the gauze going away. (Which makes sense due to a large loss of lateral surface area).
I always thought about trying to warranty my 14" unit (giggidy) saying it dind't make it to a million miles because I coudn't get 200,000 mile intervals before I had to clean it.
