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K and N Filter

I have a K and N filter in my Sport Trac, it has been there about 20000 miles. Does anyone know how often it should be cleaned? It says it can go 50000 miles between cleanings, that sounds like an awful long time.

Look at it and see if it is dirty or dry. You can clean it whenever you want.


It should be done at the 20k miles mark IMHO and maybe even more often depending on where you live and the environmental conditions.
As far as I’m concerned that 50k miles bit is nothing more than the marketing dept. at work.

Sometimes here in Oklahoma a new air filter may only be good for a few months.

id go ahead and clean and oil it whenever it looks dirty.

It says it can go 50000 miles between cleanings It says a lot of things and many of them are not true.

Your question seems to indicate that you feel that performance or mileage or engine life will suffer if you don’t clean it more often.

If you car is otherwise stock, performance and mileage are not likely to suffer. Few modern stock cars are able to benefit from better breathing air cleaners since they are designed with a good free flowing system. The need for things to help the engine breath better ended in the 1980’s.

If you are worrying about engine protection, don’t clean it now. Those oil filters do a better job of filtering after they get a little dirty and likely that is why they suggest 50,000 miles. Performance does not suffer.

The other reason not to clean it often is the potential for damage. If you get a little too much oil on it or it is not even, you can get oil going in the intake and that can damage a MAF or other sensors.

Frankly if it were mine, I would tear that K&N out and put a stock filter in there.

Right, ok. My thoughts on the marketing dept exactly. Love the K&N air filters for all the family’s vehicles, but I would never let them go 50K. Besides, they clean up easily with ordinary cleaners. I use an orange-base spray cleaner on mine and in a few minutes they are ready to go. One of the few great products out there that do what the manuf says.

I just noticed these words in my FORD 2002 Taurus owner’s manual (pg 232):

“Do not use oil-impregnated air filter elements. Failure to use the correct air filter element may result in severe engine damage. The customer warranty may be voided for any damage to the engine if the correct air filter element is not used.”

I always knew about the risk to the MAF sensor from over-oiling the filter, but I was surprised to see such wording from FORD.

“Frankly if it were mine, I would tear that K&N out and put a stock filter in there.”

Exactly what I was thinking.

It is common for people to over oil the filter. If a little is good, more is always better. The MAF is a hot wire sensor that determines total air mass by how much heat it looses. Microscopic oil coats this heating element and attracts dust just like the K&N. This dust is a thermal insulator so the sensor goes out of calibration. Incorrect fuel air ratio can cause detonation damage to internal components of the engine in extreme cases. In milder cases fuel mileage can decrease.

Also, the K&N filters allow more particulate matter to enter the engine. And the idea of an air filter is remove as much of this particulate matter as possible with the least amount of pressure drop across the filter. The more particulate matter that enters the engine, the faster the engine wears out.


Simple Test…Pull it out…Look through it at a light source (like the sun). If light has difficulty going through it then it’s time for a cleaning.

Glad I never re-oiled my K&Ns. Thanks, O H!

To tell you the truth, I have never seen any evidence that would suggest that the K&N filter cleans the air any better or worse than a paper filter.

Allowing more air through does not mean that there are larger openings allowing larger particles through. It just means that there is more open area in a given space and therefore a greater surface area to the filter element. This is the same reason diatoms are so great at filtering liquids . Everything I have worked with in waste management and environmental remediation has shown a constant stride to have something that is smaller/thinner filter better.

If you have a source to show me otherwise, I would be willing to jump off the fence.

all tests are biased. only way to prove otherwise is to try the product,and learn from experience.

While I do enjoy reading Bob the Oil Guy’s website, I do not think that his tests are overly scientific. His oil filter tests are the same. While I liked seeing how each filter is constructed it doesn’t show how any damage was done by his worst rated filters (Fram). If there was a university or an independent research company study, then I would believe it.

that method of checking filters no longer holds true.

Never purchased K&N air filters for anything other than for the car engines to breathe better for increased throttle response and we got what we were looking for. Had we not, we would have taken them back to the Walmart for a refund. So far, for the past 4+ years they have worked with 0 probs on all our family vehicles incl Ranger (1999), Lexus (2007), Alero (1999), Alero (2004), and Malibu (2005). K&N has been selling these filters for a couple decades at least.