The K&N RB-0900 is a round, clamp-on universal air filter with a 3-inch inlet flange, a 5-degree angled rubber flange, and a 4-inch height. The manufacturer builds its universal line from cotton gauze media and molded rubber flanges that absorb vibration and seal onto a tube. Unlike a disposable paper element, this filter is washable and reusable, so you can clean and re-oil it rather than replace it. It suits custom cold-air intakes, velocity stacks, and straight tubing where a stock filter will not fit, and K&N positions its universal filters for racing vehicles and other non-standard applications. Because it is universal, you need to match the 3-inch inlet and 5-degree flange angle to your own tube before buying.
No. The manufacturer's K&N cleaning instructions state that a K&N filter should never be used without oiling, so apply K&N filter oil to the pleats before installation.
The manufacturer says to service K&N filters only with K&N air filter cleaner and K&N air filter oil. Gasoline, solvents, parts cleaners, strong detergents, steam cleaning, and high-pressure car washes are all listed as harmful to the media and rubber end caps.
K&N's cleaning guidance for normal on-road use calls for service about every 50,000 miles, with more frequent cleaning in dusty conditions. Some sources list a longer interval of around 75,000 miles, so confirm the interval with the manufacturer for your application.
Because this is a universal filter, installation is a matter of fitting the 3-inch flange onto your intake tube or velocity stack and securing it with your existing clamp or hardware, so the job is generally straightforward for a home mechanic. Before installing, confirm the tube's inside diameter and mounting angle match the filter's flange. The manufacturer's cleaning instructions call for K&N cleaner, K&N oil, a soft brush, and low-pressure water. Owners should avoid heat dryers and compressed air on the media, and should re-oil lightly without saturating the element. Seat the rubber flange fully so no unfiltered air can bypass the element.
