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Discussion Starter · #1 ·
I have not been a fan of K&N air filters. Based on my knowledge of filtration in my work, my gut feeling is that a filter that relies on impaction with a sticky surface will not filter as reliably as a pore-size filter. But I didn't have any real world numbers to back this up.

I just ran across a discussion of vehicle snorkels on another forum, and found this:

BTW, I put in a K&N right after buying my truck and around 10K miles later when I tore into the engine to replace the timing chain, noticed that my intake was filthy with a fine dust. I started doing used oil analysis and was surprised at how much silica they found (around 65 ppm). That level is usually considered severe duty and usually means really short oil change intervals. I typically follow ~4K intevals on Castrol Syntec.

I promptly went back to stock Toyota filters. I now get around 5 to 10 ppm silica. The K&N certainly didn't clog like my stock filters do. But, it appeared that the reason it wasn't dirty is that it does not do a particularly good job at stopping the fine dust. As it is I replace the filter about 2 or 3 times a year, which I'd rather do than keep ingesting dirt. I recommend to everyone I know that uses a stock-fit K&N to have an analysis done (really everyone should do them periodically). Compare the silica numbers with a good traditional filter (cheap thin-paper Frams don't count) and a K&N, since silica is just a measure of how much external dirt is being sucked into the engine.
Gut feelings aren't reliable, but sometimes they are right. :evil4:
 

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thats some interesting stuff, and I have to agree.

I have my own take on the "oil charged" K&N and competitive brands.

A couple years ago I thought I would do the popular thing and purchase a K&N filter for my turbo charged VW passat. A short time later the mass air meter burnt out leaving the car stranded at my sisters house. Long story short, the oil that is used in the K&N filter was sucked into the mass air sensor and caused it to burn out. The part alone was over $200. The guys at VW said they see it all the time.
 

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Discussion Starter · #3 ·
Yeah, especially after folks do the re-oiling process, often they use too much oil and it blows off the filter.
 

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Or people like my brother who cleaned and re-oiled it every month. Haha
 

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unless you're driving in a sandstorm does it matter?
 

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Or Nashville...I've had the same paper filter in my pickup for 2 and a half years now and it still isn't dirty! We must have some clean air here.
 

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Discussion Starter · #9 ·
Kable said:
I never oil my K&N. I like to run them dry..... Amsoil does it.....
A K&N filter relies in impaction of the particulate in the oily surfaces of the filter to achieve filtration. Without oil that type of filter is nearly useless. It probably will still catch very large particulates, but that's about it.
 

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I'll post this test I found on the Mazda forums later when I'm not at work, but a guy did a compairison of K&N against other choices. All the K&N styles with oil let in more air, and a lot more dirt. The regular paper ones limited the air, but offered great filtration.

The best medium he found was the AEM & Injen dry filters. The AEM is reasonably price, it's what I run on my PGT now and couldn't be happier. The Injen dry was about $30 more than the AEM so I avoided that.

The test was a real eye opener, I'll try to find the link and post it when I get home. He made a great point though, all of K&N's claims are all made by their own company!

Actually, here is the first one I had found, there is another I can't find right now that had the AEM & Injen. But here ya go. http://www.bobistheoilguy.com/airfilter/airtest3.htm
 

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I love seeing that test....it goes along with what I notice here in the winter and that's the black filth that is in the air....very fine black sooty crap that requires soap to clean. My window sills turn black in the winter due to the effects of pollution in China being carried over across the ocean and being washed down by the rain in the winter. Imagine that stuff going in your lungs. The misconception is that the air here in the PNW is clean....well, yeah, the crap is being washed out and deposited everywhere as the air masses cross the inner Cascades.

That being said is it worth the perceived increase in HP to go with filtration that fails and leads to shorter engine life? I wouldn't risk it and have never used anything other than OEM filters in my vehicles.
 

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yea I heard that when cars go into shops with K&N air filters some technicians will take them off put them on a plastic bag and put paper filters back on there and tell the costumers theyre not good ang give the K&N filter back to the costumer
 

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I've seen a ton of people switching their K&N filters over to AFE Pro Dry air filters. From a bunch of tests that have been done most recommend the AFE since it has similar flow as the K&N, but filters the air much better. It also doesnt need to be oiled, similar to the AEM and Injen dry filters.

I'm going to be getting one here soon when I install my supercharger. I looked and don't think they make them for OEM isuzu airbox's which does suck, but i'm going to be getting a cone filter anyways.

So if anyone is putting a cone filter on their truck i'd get the AFE.
 

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GoodyMOBB said:
Kn filter ruined the turbo on my work truck. Not a cheap fix. Sucked in oil and the dust chewed up the fins...
If something chewed up your fins then it wasnt dust lol..... KN filter didnt ruin your turbo, you had other issues.
 

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so what are some proven high quality OEM filters?
 

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Wix filters are supposedly pretty good for an OEM replacement.
 

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Kable said:
GoodyMOBB said:
Kn filter ruined the turbo on my work truck. Not a cheap fix. Sucked in oil and the dust chewed up the fins...
If something chewed up your fins then it wasnt dust lol..... KN filter didnt ruin your turbo, you had other issues.
Dust/debri. That's what I was told by the mercedes tech. Said he had seen it on a few trucks using kn.
 

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my thought and test on'em was always pretty simple. Oiled filters basically filter by their "sticky" nature, so put a few pieces of double sided tape on top of your air box (inside if you want to go a step further). How sticky is the tape in a week? For me it isn't sticky after a day or two if even that long. I travel a lot of dusty trails. It's laymen as hell, but I think it's a pretty fitting demo/analogy. Sure the filter will last a little longer then the tape, but no where near as long it should. So as mentioned above to keep it in good filtering condition you have to clean and oil like once a month, but then your risky all that extra oil into the intake.
 
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