[Glowin]

I have a 2008 BMW 335, that is stage 2+, and I take it to the track a few times a year. I've had my K&N filter 3 years now, even though I've only put 20,000 miles on it (compared to the 50,000 they say it can go before cleaning's needed). So I figured it was probably a good time to clean it, and I went ahead and bought the cleaning kit before checking my filter.

But when I just checked their site for the instructions, I see it says "Cleaning your K&N Air Filter is not required if you can still see the wire screen on the entire air filter regardless of how dirty it may appear." Which seems to be what mine looks like?

If it doesn't need to be cleaned, my next question is would there actually be any DISADVANTAGE to cleaning it now, seeing I've already bought the kit? Or I should just hold on to it for another couple of years?
.

[135Pats]

I find it difficult to believe that cleaning it would be harmful. Go for it.

[Jeff@TopGearSolutions]

They are made to be cleaned.

Clean it!

It will help and it looks plenty dirty from here.

Spray the cleaning agent, let is soak a bit, then run water through it.

Let it dry for a few hours in the sun then apply the oil lightly.

[Glowin]

Thanks, all. That's what I figured, since isn't getting better flow the whole point of these filters? They got me thinking maybe something weird is going on with their filters in that it's actually good to be clogged up a bit...

On this page on their site that shows pictures of a filter where you can still see the mesh, they go as far as saying this "Filter IS NOT ready to be cleaned" as if it's bad for it to do so early... LOL.

http://www.knfilters.com/cleaning-pics.htm

In one of their older instructions, on step 11 it says "Let the dirt "build-up" work for you; it will not hurt the performance and actually help filter the air".

And I came across this nugget on this page:

http://www.atvpt.com/knairfilter.htm

The dirt particles collected on the surface of a K&N element have little effect on air flow during much of its service life because there are no small holes to clog. Particles are stopped by layers of crisscrossed cotton fibers and held in suspension by the oil. As the filter begins to collect debris, an additional form of filter action begins to take place because air must first pass through the dirt particles trapped on the surface. That means a K&N air filter continues to exhibit high air flow throughout the life of the filter while it is accumulating dirt. At the same time, the air flow for an average paper air filter can decrease dramatically as the paper element gets dirty. So as dirt accumulates, the performance advantages of a K&N air filter can increase!

WTF? That doesn't make sense.
.

[Jeff@TopGearSolutions]

Originally Posted by Glowin

Thanks, all. That's what I figured, since isn't getting better flow the whole point of these filters? They got me thinking maybe something weird is going on with their filters in that it's actually good to be clogged up a bit...

On this page on their site that shows pictures of a filter where you can still see the mesh, they go as far as saying this "Filter IS NOT ready to be cleaned" as if it's bad for it to do so early... LOL.

http://www.knfilters.com/cleaning-pics.htm

In one of their older instructions, on step 11 it says "Let the dirt "build-up" work for you; it will not hurt the performance and actually help filter the air".

And I came across this nugget on this page:

http://www.atvpt.com/knairfilter.htm

The dirt particles collected on the surface of a K&N element have little effect on air flow during much of its service life because there are no small holes to clog. Particles are stopped by layers of crisscrossed cotton fibers and held in suspension by the oil. As the filter begins to collect debris, an additional form of filter action begins to take place because air must first pass through the dirt particles trapped on the surface. That means a K&N air filter continues to exhibit high air flow throughout the life of the filter while it is accumulating dirt. At the same time, the air flow for an average paper air filter can decrease dramatically as the paper element gets dirty. So as dirt accumulates, the performance advantages of a K&N air filter can increase!

WTF? That doesn't make sense.
.

Yea, I'm not about to try to explain it either, cause I can't.

I've been dabbling with K&N filters for nearly 15 years.

If that was my filter, I'd clean it. I don't think I've ever let mine get that dirty and I've still noticed a difference in response afterwards.

[Glowin]

Yeah, I'm going to do so and will report back if I feel any difference. I can't imagine if that's what it looks like, and I live in a low dust city, how it would look if I left it to 50,000 miles as they say!!!

[muncie21]

Sounds like the K&N filters are designed similar to commercial HEPA filters. Filtration is accomplished via these principles: Straining (sieving), Interception, Diffusion, Inertial separation and Electrostatic attraction. The last item (electrostatic attraction) is not relevant to automotive filters.

More info: http://www.camfil.com/Filter-technol...of-Filtration/