NEVER!!!! You paid big bucks for the worlds best filter, why the heck be a cheapskate and use something other than the recommended product to clean it? when I was young and stupid back in the early 70s when I first started using K&N I cleaned a couple filters with solvent, like I said I was young and STUPID.
ORC Land Use Editor
VP RockGarden 4 Wheelers, Aztec, NM
RockGarden 4 Wheelers