the super tacky foam filter oils are not to be used on a k&n filter(according to them),they actually filter better when they look a bit grungy,in other words cleaning them often is unneccesary work,and every cleaning is causing damage to the filter no matter how careful you are,once every 3 years (50,000 miles according to k&n)is plenty often on a street bike,it is recomended to lightly re-oil the clean side of the filter occasionaly,every season should be enough,i know you guys can't stand having any thing that looks "dirty" on your bikes even if it hdden from site