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K&N Million-Mile Air Filter

The air filter that never gets thrown away

About.com Rating 4.5 Star Rating
User Rating 3.5 Star Rating (13 Reviews)


K&N Million-Mile Air Filter
K&N makes drop-in replacement air filters which can be cleaned rather than replaced. K&N claims the re-useable air filter saves money and landfill waste, and that their filters are less prone to air restriction as they get dirty. (Restricted airflow causes a reduction in engine power and fuel economy.) Retail prices range from $35 to $80+ depending on application.

How does the K&N filter work?

Air Filters 101
Engines produce power by igniting 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 so the engines can "breathe". A filter that is clogged with dirt will cause loss of power and fuel economy.

Most air filters use paper as their filter medium. Most cars require the filter to be checked or changed every 10,000 to 20,000 miles; when the filter is dirty it is thrown away and replaced.

How is K&N different?
K&N filters use an oiled cotton filter medium. K&N claims that not only do their filters allow freer airflow when clean, but they can absorb dirt without getting as restricted as paper filters. When the filter gets dirty, you don't throw it away; you clean and re-oil it. K&N estimates the cleaning interval to be about 50,000 miles (longer for less dusty areas). The filter is serviced with a K&N cleaning kit ($9 to $12 retail Compare Prices) which is good for 5 to 10 uses. K&N says their filter will last the lifetime of the vehicle, and covers their filters with a 10 year/million-mile warranty.

Benefits of the K&N filter

Environmental benefits
Paper air filters cannot be recycled; you have to throw the whole thing away. The K&N filter itself lasts the life of the car, and the cleaning kit uses cardboard packaging and plastic bottles which can be recycled.

Cost benefits
Cost savings depend on the application. I tested the K&N filter on our 1996 Honda Accord. Retail price for the K&N filter is about $43. (My test sample was provided free of charge by K&N.) Paper filters range from $19 to $31. Honda recommends a filter change at 15,000 miles, so for a do-it-yourselfer like me, the K&N filter and a cleaning kit will pay for itself after two changes, or about two years. For people who have their cars serviced by the dealership, installing a K&N can pay for itself in a single change.

Real-world benefits
Here's the reaility: I'm not nearly as careful as I should be about changing my cars' air filters. By the time I get around to it, the filter is usually clogged with dirt -- and that means it's costing me more at the gas pump. The K&N's longer service interval means that I can gleefully ignore it without such adverse effects.

Other issues with the K&N filter

How well does it filter?
Several readers have responded with concerns about the K&N's ability to effectively filter dirt out of the air compared to paper filters. After all, engine protection is the reason engines have an air filter to begin with. K&N insists that their filters are rigorously tested to meet OEM filtration standards.

Expert opinion: Not an issue
I discussed the issue with the owner of a reputable engine rebuilding shop. In his experience, the engines that suffered from premature wear were those in which the filters were routinely ignored. He didn't see any significant difference in wear in engines where the filters were routinely cleaned or changed, regardless of type. (He personally runs K&N filters in his own cars.)

Will the K&N increase engine power?
Many enthusiasts use K&N filters because their increased airflow boosts power, especially in certain applications. If you are replacing a clogged air filter, you will definitely see a difference. My wife Robin and I didn't see a significant power increase; that said, we weren't expecting one -- K&N sells a special intake kit for Accord owners like us who want more power. (We will be testing one in the near future.)


Installing the K&N air filter in our 1996 Honda Accord EX wagon

K&N filter is a perfect-fit replacement for the stock filter in our Honda Accord

© Aaron Gold
What I like about the K&N filter:
  • Easy installation - same as a paper air filter
  • One less maintenance task to worry about
  • Environmental advantages - less waste produced
  • Potential for better long-term fuel economy
What I didn't like about the K&N filter:
  • High initial purchase price

A useful purchase for most car owners -- even if the cost benefits aren’t huge, the benefit to the environment is significant.

User Reviews

Reviews for this section have been closed.

 5 out of 5
Great Air Filters, Member Image999

Purchased my 1st K&N filter back in the 90's for my 1992 Toyota 4x4 to help get better gas mileage, 4 cyl. Good truck made it through my 20's and 30's, beat the heck out of it. 20 years later, the truck, though a Toyota, has over 200,000 miles on it, and still runs like it did when I drove it off the floor. Has had K&N air filter in it for most of her life and only problem I've ever had (that wasnt my fault) was the water pump (nothing to do with air intake). Trucks since my lil Toy, had to change out at 100k due to issues. K&N in all my vehicles these days, just clean and oil correctly. My 2010 Nissan Titan just received a new K&N cold air intake and filter. Very nice!!!! Increased HP, Torque and so far looks like about 2 mpg increase - well once i get off the gas with the increased power. This is my keeper truck and hopefully will out live me with my K&N and proper maintenance :)

5 out of 5 people found this helpful.

See all 13 reviews

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