I’d question how much airborne (intake) particulates end up in the oil. Air filters prevent particulates from being aspirated and passing through the cylinder. Oil filters remove particulates caused mostly by engine wear and oil clumping. I don’t see how cylinder-gas particulates (of a size to cause any wear) could get past the rings or valve guides in any but a very worn engine.
K&Ns worked much like the old oil bath filters. The pore size was huge but still small enough that the particulate would touch the cotton gauze and stick to the oil. Ever get some K&N filter oil on your hands? If I recall correctly, it was sticky as all getout.
Back in the day (late 1980s) K&N filter pods worked better than the typical airbox for a Japanese inline four motorcycle. The manufacturers were beginning to claim that the newer air intakes were tuned to the bikes and that aftermarket intakes and rejetting would still result in a loss of power. I’m not familiar with today’s bikes, but I assume that there isn’t that much of an improvement.
Now, if you want to see a ***dramatic ***increase in performance, drill a few 1/2" holes in the upstream side of the airbox for a YSR50 or a Yamaha moped. Either would gain around 5-10MPH! 
We are talking about 5 to 15 micron particles here; that’s in the same ballpark as red blood cells and something like 1/4 the width of a human hair.
No kidding! And the sound from the intake on my RZ is hair-raisiing!
And you get a cool sticker for your car.
That’s where they get you. The filter actually costs 99¢.