It has been 40+ years since I bought a new K&N air filter. I remember I had to oil it. I guess I had a heavy hand and my gas mileage dropped @ 8 mpg. So I returned, it and went back to the stock element. Never bothered to try again.
I do use them on my dune buggies, 1 replacement I recently bought didn't come oiled. EMPI, K&N no longer makes the size I need.