K N claims in the re-usable air filter saves money and waste disposal, and that their filters are less likely to restricting the air as it dirty. (Restricted airflow causes a reduction in engine power and fuel economy.) Retail prices range from $ 35 to $ 80 + depending on the application.How does the K N filter?Air Filters 101Engines produce power of provoking a mixture of fuel and air. The air filter’s job is to filter out particles of dirt while allowing a free flow of air to the engine can “breathe”. A filter clogged with dirt will cause loss of power and fuel economy.Most air filters used his role as a filter medium. Most cars require the filter to be checked or changed every 10000 to 20000 miles; when the filter is dirty, is thrown away and replaced.How is K N different?K N filters use an oiled cotton filter medium. K N claims that its filters not only allows the flow of fresh air when clean, but they can absorb dirt without limitation as filter papers. When the filter gets dirty, not pull away, clean and re-oil. K N estimates that the cleaning interval is about 50000 miles (longer for less dust). The filter is served with a K N cleaning kit ($ 9 to $ 12 Compare Prices retail), which is good for 5 to 10 uses. K N said its filter will last for the lifetime of the vehicle, with its filters and covers 10 years and millions of miles warranty.Benefits of K N filterBenefits for the environmentPaper air filters can not be recycled; you have to throw the whole thing away. The K N filter itself lasts the life of the car, and cleaning kit used cartons and plastic bottles that can be recycled.Cost benefitsThe cost savings will depend on the application. I tried K N filter in our 1996 Honda Accord. The retail price for K N filter is approximately $ 43. (My test sample was provided free of charge by K N) filter papers ranging from $ 19 to $ 31. Honda recommends a change to filter 15000 miles, so for a do-it-yourself like me, K N filter and a cleaning kit will take care of itself after two changes, or about two years. For people who have their car serviced by the dealership, the installation of a K N could pay for itself in a single shift.In the real world benefitsThis is the reaility: I am not as careful as I should be on changing my cars’ air filters. By the time I get around it, is the filter is usually clogged with dirt – and that means more to me to pump gas. The K N longer service intervals means that you can blithely ignore that, without harmful effects.Other issues with the K N filterHow well does it filter?Several readers have responded with concern for the K W’s ability to effectively filter out dirt air compared to filter papers. After all, protecting the engine is why engines have an air filter to begin. K N insists that its filters are rigorously tested to meet standards filtration OEMs.The expert opinion: Not an issueI discussed the issue with the owner of an engine rebuilding shop reputation.