Most people believe that all air filters function on a go/no go basis where dirt particles that are larger than the openings in the filter media are trapped while particles that are smaller than the openings can pass right through. A dry paper air filter does function in this manner. That's why paper filters are so restrictive to air flow. The openings in this type of filter have to be very small to filter efficiently.

    The oiled cotton filter media used in the K&N air filter functions in an entirely different manner. There are scientific principles that determine how an air filter removes dirt particles from the air stream. The first of these principles is known as interception, which applies to dirt particles traveling with the air stream. Air flow will always take the shortest path and as the air is forced to flow around the filter's fibers some of the particles will contact the sides of the fibers and be captured. These particles are then held in place by the oil or tacking agent in the fiber.

    Another principle is known as impaction, which mostly affects larger or heavier dirt particles. Impaction occurs when the inertia or momentum of the particle causes it to deviate from the flow path. In other words the heavy particles do not follow the air stream around the filter's fibers but instead they run straight into the fibers and are captured.

    The most important principle for our use is diffusion, which deals with the laws of physics that govern the motion of very small dirt particles. Small particles are highly affected by the forces in the air stream. Forces such as velocity changes, pressure changes, turbulence caused by other particles and interaction with the air molecules cause these very small particles to become random and chaotic. As a result, these particles do not follow the air stream and their erratic motion causes them to collide with the filter's fibers. This phenomenon enables an air filter to capture dirt particles that are much smaller than the openings in the media. In addition, the way that dirt collects or loads on the K&N filter is very different. A paper filter exhibits "surface loading" which means dust collects only on the surface of the media. In contrast, K&N filters exhibit "depth loading". The multiple layers of cotton fibers provide many levels of dust retention. This characteristic allows the K&N filter to hold significantly more dirt per square inch of media than the average paper filter. Utilizing these scientific principles, K&N has been able to design an air filter that is very free flowing while also being highly efficient at removing dirt from the air.


    The K&N Washable Cabin Air Filter is the first of its kind designed to replace your vehicle's stock cabin air filter with a washable and reusable version that cleans and freshens incoming air. Watch the video above for more information on how cabin air filters work. K&N Cabin Air Filters are designed to be cleaned and reused over and over again. Using a combination of an advanced synthetic filter media and K&N Refresher™ spray, the K&N Washable Cabin Air Filter grabs and holds dust particles.

    Does your vehicle have a cabin air filter?
    Since automotive cabin air filters have only recently been integrated into US automobile AC/heating systems, many vehicle owners do not realize their car is equipped with a cabin air filter. To determine if your vehicle has a cabin air filter you would first check the owner’s manual. You can also inspect the vehicle for the location of the cabin air filter which is typically found in one of these three places:

    • Under the hood, near the windshield
    • Underneath the dashboard
    • Behind the glove compartment

    K&N air filter cleaning supplies are available for K&N cotton, synthetic and heavy duty synthetic air filters. K&N OE replacement air filters have cotton media and are cleaned with K&N Power Kleen Industrial Strength Degreaser and then oiled with a specialized blend of filter oil.

    • High Flow Rates
    • Exceptional Filtration 
    • Strong and Durable

    Oil Filters for Cars, Trucks, SUV and more!

    K&N Oil Filters provide outstanding filtration levels and a high oil flow rate. They are able to handle heavy duty applications and helps block foreign material. They are great with synthetic and conventional oils! K&N offers Premium Wrench-Off®Performance Gold®, Performance Silver®, Cartridge and Billet Oil Filters for a range of vehicle applications and service providers.

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