I serviced my K&N air filter. It suprises me how dirty it gets. I have the 1 that goes in the stock air cleaner & it much bigger/wider than the stock filter. It really catches a lot of dirt at the front. You just spray the K&N cleaner on the outside of the filter & let it sit for 10 minutes, then rinse from the inside out with cool water.
I was almost out of the oil, so I bought a K&N spray oil can at Cycle Gear a few weeks back & it's much easier to use than the oil in a bottle that you have to squirt on each pleat. That's a mess & a pain. They have about 8 different air filter oils at the store, but the K&N was within a dollar, so I stuck with it. Some of the oils are for the foam air filters on a dirt bike.