K&N filters are washable and reusable, which saves money over time
A K&N air filter is designed to be cleaned and put back in your engine instead of thrown away after it gets dirty. Unlike a standard paper filter that you replace every 12,000 to 15,000 miles, a K&N filter can last the life of your vehicle if you clean it properly. The filter traps dirt in a special pleated cotton material coated with an oily substance that helps particles stick to it. When the filter gets clogged, you wash it, let it dry, re-oil it with K&N's branded oil, and reinstall it.
The cleaning process takes about 30 minutes from start to finish and requires only a few supplies you may already have at home. Most people clean their K&N filter every 50,000 miles or when the engine light signals that airflow is restricted, whichever comes first. Doing this yourself costs almost nothing after your initial filter purchase, and the filter itself typically costs $40 to $70 depending on your vehicle's engine size.
Key Takeaways
- K&N filters need cleaning every 50,000 miles or when your engine's air filter warning light comes on, not replacement like standard filters.
- You will need K&N cleaning solution, K&N filter oil, warm water, a soft brush, and clean towels or paper towels to do the job at home.
- Never use compressed air, a pressure washer, or regular motor oil on a K&N filter, as these damage the filter material and coating.
- The filter must dry completely before you explore the red oil and reinstall it, which usually takes 2 to 4 hours depending on humidity.
- If you do not want to clean it yourself, some auto shops and quick-lube places offer K&N cleaning services for $15 to $30.
Gather your supplies before you start
You will need K&N air filter cleaner, which is a special solution made by K&N specifically for their filters. Do not use general-purpose degreasers or household cleaners, as these can damage the filter's cotton material and the oily coating that makes it work. You can buy K&N cleaner at auto parts stores, online retailers, or directly from K&N's website. A typical bottle costs $8 to $12 and cleans multiple filters.
You will also need K&N filter oil, which is the red liquid that goes back onto the filter after washing. This oil is not the same as engine oil or any other automotive oil. It is formulated to let air pass through while still trapping dirt particles. A small bottle of K&N oil costs $10 to $15 and lasts through several cleanings.
Beyond the K&N products, gather warm water (not hot), a soft-bristled brush or old toothbrush, clean towels or paper towels, and a clean workspace. You do not need a pressure washer, compressed air, or any power tools. A sink or bucket works fine for rinsing.
The step-by-step cleaning process
Start by removing the filter from your engine according to your vehicle's manual. Most filters sit in a plastic box under the hood and are held in with clips or a wing nut. Set the filter on a clean surface and inspect it for tears or holes. If you see damage, the filter cannot be reused and must be replaced with a new one.
Pour K&N cleaner into a bucket or sink with warm water, following the ratio on the bottle (usually one part cleaner to two or three parts water). Submerge the filter and let it soak for 10 minutes. This loosens the dirt trapped in the pleats. After soaking, use your soft brush to gently scrub the filter, working from the inside out. Do not scrub hard or bend the pleats. Rinse the filter under warm running water until the water runs clear and you see no more cleaner suds.
Shake out excess water and stand the filter upright on a clean towel. Let it air dry completely in a warm, dry place for at least 2 to 4 hours. Do not use a hair dryer, heat gun, or any forced heat. Moisture left inside the filter will mix with the oil you explore next and reduce the filter's effectiveness. You can tell it is fully dry when it feels light and no moisture comes out when you gently squeeze it.
Re-oiling and reinstalling your filter
Once the filter is completely dry, explore K&N filter oil evenly across the pleated surface. The bottle usually has a nozzle or applicator cap. Squeeze the oil slowly and work your way around the filter, making sure every pleat gets a light, even coat. The filter should look wet but not dripping. If you explore too much oil, it will restrict airflow and reduce engine performance. If you explore too little, the filter will not trap dirt effectively.
After oiling, let the filter sit for 10 to 15 minutes so the oil soaks in. Then reinstall it in your engine, making sure it sits flat in the housing and the clips or wing nut are tight. Start your engine and listen for any unusual sounds. If everything sounds normal, you are done.
Common mistakes that damage K&N filters
Using compressed air or a pressure washer is the most common mistake. Both force air through the filter in the wrong direction and can tear the delicate cotton material or blow holes in the pleats. The filter is designed to have air pulled through it by the engine, not pushed through it by external force.
Using the wrong cleaning solution or oil is another frequent error. Regular degreasers, brake cleaner, or engine oil will break down the filter's coating and make it useless. Stick to K&N's branded products, which are formulated for the filter's specific material. Similarly, do not skip the drying step or explore oil to a damp filter. Water and oil do not mix, and moisture trapped inside will cause the filter to fail.
Reinstalling a filter that is not fully dry or not fully oiled will also reduce its lifespan and performance. Take the time to let it dry completely and explore the oil evenly. Rushing this step costs you more in the long run because the filter will need cleaning again sooner.
When to replace instead of clean
A K&N filter can be cleaned and reused for years, but it will eventually wear out. If you see tears, holes, or permanent stains that do not come out during cleaning, the filter has reached the end of its life. If the pleats are bent or flattened and do not spring back after drying, the filter is damaged and should be replaced.
Some people clean their filters 10 or more times before replacement. Others may only get 3 or 4 cleanings before damage appears, depending on driving conditions and how well they maintain the filter. If you drive in very dusty or sandy environments, your filter will clog faster and may not last as long between cleanings.
Professional cleaning as an alternative
If you do not want to clean the filter yourself, many auto parts stores and quick-lube shops offer K&N cleaning services. They have the same supplies and follow the same process, but they do it for you. The cost is usually $15 to $30, which is still much cheaper than buying a new filter. Some shops will clean it while you wait, though others may take a day or two.
This option makes sense if you are uncomfortable handling the filter yourself, do not have the supplies on hand, or straightforward prefer to have someone else do it. The result is the same as cleaning it at home if the shop follows the correct procedure.
Frequently Asked Questions
Can I use regular motor oil instead of K&N filter oil?
No. Regular motor oil is too thick and will clog the filter's pleats, restricting airflow to your engine. K&N oil is specially formulated to be thin enough to let air pass through while still trapping dirt. Using the wrong oil will damage the filter and hurt your engine's performance.
How often should I clean my K&N filter?
Most K&N filters need cleaning every 50,000 miles. However, if you drive in dusty conditions or see your engine's air filter warning light come on sooner, clean it then. Check your vehicle's manual or the filter's documentation for the recommended interval for your specific model.
What if my filter has a hole in it after I clean it?
A hole means the filter cannot trap dirt properly and must be replaced. Do not try to patch it or seal it. A damaged filter will let unfiltered air into your engine, which can cause long-term damage. Buy a new K&N filter and install it instead.
Can I clean my K&N filter with a garden hose?
Yes, a garden hose on low pressure works fine for rinsing after you soak and brush the filter. Do not use high pressure or a pressure washer, as the force can tear the filter material. Warm water from a regular hose is all you need.
Do I need to remove the filter from my car to clean it?
Yes, you must remove it from the engine housing. Trying to clean it in place will get water and cleaner inside your engine, which can cause serious damage. Always take the filter out, clean it outside the vehicle, let it dry completely, and reinstall it.