K&N Air Filter Cleaner K&N Air Filter Cleaner efficiently breaks down dirt accumulation and previous filter oil from K&N Filtercharger air filters. Its biodegradable composition ensures it is harmless to paint, plastic, cast aluminum, and rubber, and can be simply rinsed off with water. Features Formulated to clean K&N Filtercharger air filter elements Dissolves dirt buildup and old filter oil Washes away with water Biodegradable, safe on paint, plastic, cast aluminum and rubber Instructions included 1 gallon refill bottle