I have used K&N on all my short course race trucks with excellant results. However after cleaning a K&N the gauze takes quite a while to dry, I used to allow two days. As much as I like them, I will not be using one on my KX500. I have had the stock foam swell up, a UNI filter come apart at the glued seam ( not too funny from my standpoint) and now am using a pair of Twin Air filters, that seem to hold up great. I have two filters, I keep one clean and oiled in a plastic resealable tub, and the other is on the bike. I usually change filters after two days riding ( about fifteen gallons of gas). I have been using the No Toil oil and cleaner, but am considering changing to a less costly brand. I would gladly try the "Ready Filter" but cannot find one on thier application chart. ( for ten bucks, clean and preoiled seems like a good deal) What oil filter oil is everyone using?