K&N How to Clean Air Filter

Cleaning a K&N air filter is a straightforward, cost-effective process that can significantly extend the life of your filter and maintain your engine's performance. Unlike disposable paper filters, K&N's cotton gauze filters are designed to be cleaned and re-oiled, offering long-term value and superior airflow. The entire process, from removal to reinstallation, typically takes under an hour and requires only a specific K&N cleaning kit. Properly maintaining your K&N air filter ensures it continues to protect your engine from harmful contaminants while allowing for optimal air intake. This guide will provide a detailed, step-by-step walkthrough of the correct and safe method to clean your K&N air filter, emphasizing the critical dos and don'ts to avoid common mistakes.

The first and most crucial step is gathering the correct materials. Using the wrong products can permanently damage the filter's delicate cotton media. You must use a cleaner designed for oiled cotton filters. The ​K&N High-Flow Air Filter Cleaning Kit​ is the recommended choice, as it contains everything you need: a specialized cleaner that dissolves dirt and old oil without harming the filter, and a bottle of K&N's specific High-Flow Air Filter Oil. Do not substitute household cleaners, degreasers, brake cleaner, or gasoline, as these can be too harsh and destroy the filter material. You will also need access to a low-pressure water source, such as a garden hose with a gentle spray nozzle, and a clean, shaded area to work.

Before you begin, allow the filter to cool down completely if the engine has been recently running. Locate the air filter housing under the hood of your vehicle. The housing is typically a large, black plastic box near the engine. Carefully unclip or unscrew the fasteners holding the housing lid in place. Lift the lid and remove the filter. Take a moment to inspect the filter's general condition. Also, take note of which side of the filter faced the engine; this is usually obvious, but a quick mental note will ensure correct reinstallation later.

Begin the cleaning process by gently tapping the filter on a solid surface, like a clean patch of pavement, to dislodge loose, dry dirt and debris. This preliminary step helps remove the bulk of the surface contamination before wetting the filter. Next, lay the filter on a clean surface and spray the K&N Air Filter Cleaner evenly across the entire surface of the filter. Be sure to cover both the front and back sides. The cleaner will start to dissolve the grime and the old, sticky filter oil. Allow the cleaner to soak into the filter material for approximately 10 minutes. Do not let the cleaner dry on the filter.

After the cleaner has soaked, it is time to rinse the filter. Hold the filter with the dirty side facing down, away from the engine side. Using a garden hose with a gentle stream of cool water, rinse the filter from the cleanest side (the engine side) towards the dirtiest side. This technique helps push contaminants out of the cotton pleats rather than driving them deeper in. Continue rinsing until the water runs clear and all the dissolved dirt and old oil has been washed away. Avoid using a high-pressure washer, as the forceful stream can damage the delicate cotton gauze material and the rubber sealing ring around the filter's top.

Once the filter is thoroughly rinsed, you must allow it to dry completely. This is a non-negotiable step. The filter must be 100% dry before applying the new oil. The best method is to let the filter air dry naturally in a shaded, clean area. Depending on temperature and humidity, this can take one to three hours. Do not use compressed air to dry the filter, as this can also damage the media. Never attempt to speed up the drying process by using a heat source like a hair dryer, heat gun, or placing it near an oven. Excessive heat can warp the rubber end caps and compromise the structural integrity of the filter.

Applying the new filter oil is the most critical step in the recharge process. The oil is what actually traps the tiny, harmful particles that the filter media alone cannot catch. K&N Air Filter Oil is a specially formulated, high-flowing red oil. Shake the bottle of oil vigorously for at least 30 seconds before use. Slowly and carefully apply a thin, even coat of oil over the entire surface of the clean, dry filter. Start by drizzling the oil along the crown of each pleat. Use your hands to gently spread the oil across the entire surface, ensuring every part of the cotton media is saturated but not dripping wet. The goal is a light, even coverage. An over-oiled filter can restrict airflow and potentially harm your engine's Mass Air Flow (MAF) sensor if excess oil is drawn into the intake system.

Once the oil is applied, you may notice it is a bright, vibrant red. To ensure the oil has properly wicked into the cotton material, gently press a clean, white paper towel against the oiled surface. If a significant amount of red oil comes off on the towel, the filter may be slightly over-oiled. Simply press the towel against the filter in several places to absorb the excess. When the towel shows only a faint pink trace, the oil level is correct. The filter should not look soggy or saturated; it should have a uniform, reddish hue.

The final step is reassembly. Before placing the freshly cleaned and oiled filter back into the housing, take a moment to wipe out the inside of the air filter box with a clean, damp cloth to remove any accumulated dust or debris. Carefully place the filter back into the housing, ensuring it is seated correctly and that the rubber gasket is making a proper seal with the housing. Replace the lid and securely fasten all the clips or screws. A proper seal is essential to prevent unfiltered air from bypassing the filter and entering the engine.

Understanding the frequency of cleaning is key to maintaining engine health. K&N generally recommends cleaning the filter every 50,000 miles under normal highway driving conditions. However, if you frequently drive in severe conditions—such as on dusty, unpaved roads, in areas with high pollution, or for frequent short trips where the engine does not fully warm up—you should inspect the filter every 10,000 to 15,000 miles. A visual inspection is the best guide. Hold a light source behind the filter and look through the media. If you cannot see light through a significant portion of the pleats, it is time for a cleaning. Regular maintenance following this detailed procedure will ensure your K&N air filter provides superior performance and protection for many years and thousands of miles.