# K&N Filter Dissected



## mikeeitup (Aug 27, 2013)

Wow that's crazy. I sure wish I saw this before I bought my drop in filter....
Mike


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## Merc6 (Jun 8, 2013)

I wonder if the Spectre ones are as bad or worse... Good to know you can use your K&N filter media as a tourniquet if you skip oiling process when you wash it.


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## giantsnation (Oct 11, 2012)

The scary part here is that because the oil has gotten such a bad rap (most of the time its user error) that people are starting to clean these and use them *dry*!!


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## mr overkill (Dec 1, 2013)

Xtreme you stirring the pot ? JUST KIDDING hope those pictures help explain what people have been saying !!


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## sx sonic (Nov 25, 2013)

You're lieing 
Jp, looks a lot worse than I thought.


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## XtremeRevolution (Jan 19, 2012)

giantsnation said:


> The scary part here is that because the oil has gotten such a bad rap (most of the time its user error) that people are starting to clean these and use them *dry*!!


You want to know what the disgusting part of this really is? That filter has 20k miles on it. That's it. Get a load of the BS from the K&N website:



> If you have not experienced a decrease in mileage or engine performance, chances are your filter is fine and does not yet need cleaning. To be more specific, the filter does not require cleaning if you can still see the wire screen on the entire air filter regardless of how dirty it may appear. When the screen is no longer visible some place on the filter, it is time to clean it. When used in normal paved road, street or highway conditions, our replacement air filters that fit in the factory air box should require cleaning every 50,000 miles and *our large conical filters on an intake system should require cleaning every 100,000 miles*. When used in dusty or off-road environments, our filters will require cleaning more often. We recommend that you visually inspect your filter once every 25,000 miles to determine if the screen is still visible.


I don't want to know what this engine would have looked like internally in another 80k miles on that exact same filter. I wouldn't exactly call Terry's driving on this "dusty environments."


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## prince_bigd (Jul 16, 2013)

Thats about what Ive found when Ive dissected an old K&N drop in filter that I had. Its pitiful. 

Just to offer another option AFE also makes a dry synthetic filter. The AFE Pro Dry S. I honestly think from the testing ive saw the Amsoil filter does filter slightly better but not much and both offer similar flow with the AFE flowing slightly better. This fits with the filtration/flow trade off. Either one is worlds ahead of K&N. 
the part number on the AFE is 21-91062. I dont know if any of our supporting vendors sales AFE though but if so its another good replacement. 

I just happened to go with the AFE because I had previously used an AFE filter on my HHR and I hadnt found the AEM/Amsoil filter for our cruze. Either one is such a better selection than K&N. 

On this topic does either one offer a drop in filter for our other members still using a stock box?


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## XtremeRevolution (Jan 19, 2012)

prince_bigd said:


> Thats about what Ive found when Ive dissected an old K&N drop in filter that I had. Its pitiful.
> 
> Just to offer another option AFE also makes a dry synthetic filter. The AFE Pro Dry S. I honestly think from the testing ive saw the Amsoil filter does filter slightly better but not much and both offer similar flow with the AFE flowing slightly better. This fits with the filtration/flow trade off. Either one is worlds ahead of K&N.
> the part number on the AFE is 21-91062. I dont know if any of our supporting vendors sales AFE though but if so its another good replacement.
> ...


Consider a few factors like pleat density as well. That INJEN filter is very dense, and the AFE is about the same density as the K&N filters from what I've seen. Neither makes a drop-in for our cars.


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## NBrehm (Jun 27, 2011)

All the cotton/gauze type filters are like that. That is why they are multi layer and use oil. Not exactly sure what you expected to see from a cotton filter?


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## NBrehm (Jun 27, 2011)

The fact it is a short ram intake doesn't help either since it picks up all the contamination from the engine bay you normally wouldn't get on a stock intake. Why you are supposed to clean them every 15,000 miles.


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## XtremeRevolution (Jan 19, 2012)

NBrehm said:


> The fact it is a short ram intake doesn't help either since it picks up all the contamination from the engine bay you normally wouldn't get on a stock intake. Why you are supposed to clean them every 15,000 miles.


According to K&N FAQ, the panel filter is 50k miles and these are 100k miles normal service or 25k miles severe service. 15k miles is probably more reasonable, but I wouldn't consider these conditions to be severe service.


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## spacedout (Dec 7, 2010)

XtremeRevolution said:


> According to K&N FAQ, the panel filter is 50k miles and these are 100k miles normal service or 25k miles severe service. 15k miles is probably more reasonable, but I wouldn't consider these conditions to be severe service.


The stock paper filer GM says is good for 45,000 miles, I changed mine at 33,000 and it looked almost brand new still. I can't imagine needing to clean a K&N drop in filter even every 30,000 miles from what I seen. 

The filter GM uses is very oversized for an engine of this size, almost double the size of the one from my old 3800. I'm guessing this is the reason for the long service life.


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## SunnyinHollister (Mar 17, 2011)

XtremeRevolution said:


> According to K&N FAQ, the panel filter is 50k miles and these are 100k miles normal service or 25k miles severe service. 15k miles is probably more reasonable, but I wouldn't consider these conditions to be severe service.


Actually the filtering efficiency improves as the filter loads up so the 50k/100k service intervals are correct in most cases. Now that being said you will never find a K&N air filter on any of my vehicles.


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## prince_bigd (Jul 16, 2013)

To me that is just saying that it will let less dirt through once it becomes clogged with enough dirt. Not exactly a great sales pitch when you think of it that way. Ive also saw some testing where the overall dust load capacity decreases with subsequent washes and reoils.


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## Patman (May 7, 2011)

prince_bigd said:


> To me that is just saying that it will let less dirt through once it becomes clogged with enough dirt. Not exactly a great sales pitch when you think of it that way. Ive also saw some testing where the overall dust load capacity decreases with subsequent washes and reoils.


I bought the cleaning kit for the K&N I had and cleaned it multiple times. No matter what I did I always seemed to over oil it. That being said I went to my local Ac Delco supplier and bought a factory filter and the car runs fine. Something can be said for stock. If there was a better way of doing something, don't you think the manufacturer wouldn't have done it?


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## xxxxxxxxTheSkunkWorks (Jan 24, 2014)

While I certainly don't want to ingest anything large enough to cause premature wear or damage, on the other side of the coin it may be worth bearing in mind that over-filtration can cause an unnecessary restriction without additional benefit (i.e., beyond the point of diminishing returns). My understanding, limited as it may be, is that anything smaller than ~20 microns isn't large enough to increase wear, despite the extent to which many a popular oil filter may go for advertising purposes. So, in the name of following scientific method, however sensational may be the visual evidence (my jaw hit the floor too), I'm guessing that I'm not the only one who would be very interested in seeing hard data on the particulates passed thru a properly maintained K&N under normal operating conditions. My $.02


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## The_Madcat (Oct 6, 2012)

Patman said:


> If there was a better way of doing something, don't you think the manufacturer wouldn't have done it?


Not that I am promoting K&N here but that statement is way off. It should say "If there was a cheaper way of doing something...."


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## XtremeRevolution (Jan 19, 2012)

TheSkunkWorks said:


> While I certainly don't want to ingest anything large enough to cause premature wear or damage, on the other side of the coin it may be worth bearing in mind that over-filtration can cause an unnecessary restriction without additional benefit (i.e., beyond the point of diminishing returns). My understanding, limited as it may be, is that anything smaller than ~20 microns isn't large enough to increase wear, despite the extent to which many a popular oil filter may go for advertising purposes. So, in the name of following scientific method, however sensational may be the visual evidence (my jaw hit the floor too), I'm guessing that I'm not the only one who would be very interested in seeing hard data on the particulates passed thru a properly maintained K&N under normal operating conditions. My $.02


This has already been debated in other threads. Google "turbo dusting." SAE testing has shown that particles in the 5-20 micron range cause 80% of the wear engines experience. This is why diesel guys run bypass oil filtration systems. Also bear in mind the difference between absolute and nominal ratings. Most companies use a nominal rating to make themselves look better. 

The lack of filtration in K&N filters shows up with elevated silicone levels in the oil during oil testing analysis. That's reason enough for me to avoid them.

There isn't any point in debating this to be honest. The difference between paper stock with a resonator bypassed and a K&N intake is at best 1-3hp. As enthusiasts, we are supposed to want the best for our cars, not fight to settle for the bare minimum or mediocre. If you want more flow, increase filtration surface area instead of reducing filtration efficiency. 

Sent from mobile.


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## XtremeRevolution (Jan 19, 2012)

Testing:

http://www.bobistheoilguy.com/airfilter/airtest3.htm

http://www.nicoclub.com/archives/kn-vs-oem-filter.html

Bear in mind the AMSOIL filters tested there were their older filters, not the newer EA nanofiber filters. 

Sent from mobile.


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## giantsnation (Oct 11, 2012)

XtremeRevolution said:


> This has already been debated in other threads. Google "turbo dusting." SAE testing has shown that particles in the 5-20 micron range cause 80% of the wear engines experience. This is why diesel guys run bypass oil filtration systems. Also bear in mind the difference between absolute and nominal ratings. Most companies use a nominal rating to make themselves look better.
> 
> The lack of filtration in K&N filters shows up with elevated silicone levels in the oil during oil testing analysis. That's reason enough for me to avoid them.
> 
> ...


:sigh: Exactly. I think the important thing here is filtration not performance. A K&N short ram with the new Injen filter won't do much more for performance verus K&N panel filter and resonator bypass.


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## XtremeRevolution (Jan 19, 2012)

giantsnation said:


> :sigh: Exactly. I think the important thing here is filtration not performance. A K&N short ram with the new Injen filter won't do much more for performance verus K&N panel filter and resonator bypass.


It will at higher power levels. BNR has a sonic running 13.7 in the 1/4 mile. Stock or stock tuned? Not worth it. These intakes are cosmetics and sound entirely until you start making real power. People who make a lot of power have long accepted that their longevity is compromised, but that's still no reason to make matters worse by compromising filtration. 

Sent from mobile.


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## xxxxxxxxTheSkunkWorks (Jan 24, 2014)

Point taken, and appreciated. FWIW, I'll be holding off on the K&N when I bypass the resonator this weekend, and do plan on reading up on turbo dusting...


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## NBrehm (Jun 27, 2011)

spacedout said:


> The stock paper filer GM says is good for 45,000 miles, I changed mine at 33,000 and it looked almost brand new still. I can't imagine needing to clean a K&N drop in filter even every 30,000 miles from what I seen.
> 
> The filter GM uses is very oversized for an engine of this size, almost double the size of the one from my old 3800. I'm guessing this is the reason for the long service life.


Am I the only one that WANTS to see a dirty air filter? No one seems to be addressing the point if the filter is filthy it is picking up the dirt. All a clean air filter at 45,000 miles tells me is you either drive on the cleanest roads ever or that dirt is in your engine. So again what is the issue with a dirty filter?


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## NBrehm (Jun 27, 2011)

TheSkunkWorks said:


> My understanding, limited as it may be, is that anything smaller than ~20 microns isn't large enough to increase wear, despite the extent to which many a popular oil filter may go for advertising purposes.


That is purely speculative, it also depends on how many contaminants get in, not just size. Not the best analogy but if you threw one grain of sand at a piece of metal at very high speed it isn't going to do much damage, now sand blast that same piece of metal with sand of the same size and see how much damage it does. Granted that is an extreme comparison.


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## NBrehm (Jun 27, 2011)

XtremeRevolution said:


> According to K&N FAQ, the panel filter is 50k miles and these are 100k miles normal service or 25k miles severe service. 15k miles is probably more reasonable, but I wouldn't consider these conditions to be severe service.


I don't care about that, I clean it when it needs to be cleaned. You can go 15,000 miles on an oil change too, which may or may not be wise depending on where and how you drive. what I DO care about is that the filter keeps dirt out of my engine. And a filthy air filter is doing it's job


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## spacedout (Dec 7, 2010)

NBrehm said:


> Am I the only one that WANTS to see a dirty air filter? No one seems to be addressing the point if the filter is filthy it is picking up the dirt. All a clean air filter at 45,000 miles tells me is you either drive on the cleanest roads ever or that dirt is in your engine. So again what is the issue with a dirty filter?


You are correct though dirt does actually increase filtering efficency, however I like to make sure the dead bees and leaves have not taken over(blocking flow). My point was the factory filter has a 45,000mile service life so cleaning a K&N pannel that has a 50,000 mile service life before that point is excessive and unneeded. 

I was checking my filter as it had been 2 years and over 30,000 miles, typically my filter & housing are pretty dirty by this point with other cars. I was shocked the filter was so clean and nothing in the housing. Since I was already in there I changed the filter anyway($10 on rockauto for the ACdelco filter), next time i am going 50-60K before I even check it.


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## sciphi (Aug 26, 2011)

This is why I stick to OEM airboxes, or use a paper/non-cotton conical filter.



NBrehm said:


> Am I the only one that WANTS to see a dirty air filter? No one seems to be addressing the point if the filter is filthy it is picking up the dirt. All a clean air filter at 45,000 miles tells me is you either drive on the cleanest roads ever or that dirt is in your engine. So again what is the issue with a dirty filter?


I like seeing a dirty air filter also. It's nice to see evidence that the filter is doing its job. 

I also like seeing squeaky clean intake tubing behind that dirty air filter.


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## grs1961 (Oct 23, 2012)

NBrehm said:


> All the cotton/gauze type filters are like that. That is why they are multi layer and use oil. Not exactly sure what you expected to see from a cotton filter?


You'd think all the screaming sheilas in this thread had never seen an oiled-cotton air-filter taken apart before - oh, right, they haven't, too bloody young!


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## prince_bigd (Jul 16, 2013)

Hey now this sheilas a bloke....... lmao sorry had to say it. In all honestly I knew that cotton gauze is cotton gauze no matter how they market it. Only thing that truly turned me against K&N was multiple independent tests which put its fine particle filtration so far behind factory paper and even other aftermarket filters. Ill admit that it also was among the best flowing but actually was outflowed in some tests by AEM and AFE dry flo filters and not that far ahead of the Amsoil/injen which tend to be as good as paper or better going by MAP frequency for airflow rate. All filters like any part are a balance. Some get it better than others. Ive run K&N on most of my N/A vehicles with no issues, but after seeing the tests and knowing how much forced induction magnifies the effect damaging particles have I feel safer running a better filtering material and just going with a larger surface area to meet or exceed the total airflow of my old filter.


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## NBrehm (Jun 27, 2011)

spacedout said:


> You are correct though dirt does actually increase filtering efficency, however I like to make sure the dead bees and leaves have not taken over(blocking flow). My point was the factory filter has a 45,000mile service life so cleaning a K&N pannel that has a 50,000 mile service life before that point is excessive and unneeded.
> 
> I was checking my filter as it had been 2 years and over 30,000 miles, typically my filter & housing are pretty dirty by this point with other cars. I was shocked the filter was so clean and nothing in the housing. Since I was already in there I changed the filter anyway($10 on rockauto for the ACdelco filter), next time i am going 50-60K before I even check it.


Dirt on any air filter will increase filtration because it reduces open space for dirt to get through, doesn't matter if it is cotton paper or foam. My stock filter was shot at 20,000 miles. I live where there is dirt and dust. You cannot put a "service life" on an air filter, period. It should be checked every time you change your oil since there is really no way to know how dirty it is. If you want to wait 50,000 before you even look at yours have at it, but I don;t think that it is something that should be encouraged for everyone. Takes 5 minutes and costs $0 to pull the filter out and look at it. Why would you think a re-useable filter is only good for 50k? Any of them, regardless of brand, should easily outlast your car.


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## pL2014 (Dec 29, 2013)

This and other threads on this forum have convinced me not to use an K&N filter in the Cruze. I've laid out my position on this in another thread, but it was sort of off-topic, so I'll comment here as well. 

I don't think the K&N drop in filters are as bad as the neigh-sayers say. My main reason for using one on my last car (which I traded at 212k with no internal engine trouble) was the $$ savings. That car called for a 15k air filter change interval. I was buying filters all the time and I figured after about 60k, I had paid for the K&N. Now however, I'm seeing 45k as the severe service interval on the Cruze (with checks at every oil change) so I'm thinking it would take more like 150-200k miles on the Cruze to pay for the K&N. Most of the reputable tests I've seen on the K&N say it "flows" about 1-2% better and filters about 98-99% as well. For me, air flow is a non-issue since it's clear that an unmodified engine is already getting the air it needs with a paper filter. So if the costs are about same, I might as well use paper and get 100% of the filtration. (Also from what I've seen, Delco air filters seem to test very well for filtration). Again, I had no issues with my K&N before, but I've rethought my position on the subject for the Cruze.


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## NBrehm (Jun 27, 2011)

The other danger with an oiled filter with cars with a MAF is also over oiling and getting contamination on the wires of the MAF. But I still seem to be drawing a blank on why an air filter getting dirty is such a bad thing, regardless of mileage. It's one thing to say it isn't cost effective, but ht edebate here seems to be it gets too dirty too fast, which seems silly to me. If that dirt was in the intake tract anyway and the cotton/oil filter is dirtier than a paper one, well I would say that is empirical evidence the cotton one is filtering better.


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## NBrehm (Jun 27, 2011)

I mean X did you find a lot of dust and dirt in the intake tract of your car after removing the K&N? I've run K&N and dry flow cotton air filters for years and I have never had an inkling of issues with dirt getting past it into the intake tract.


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## XtremeRevolution (Jan 19, 2012)

NBrehm said:


> The other danger with an oiled filter with cars with a MAF is also over oiling and getting contamination on the wires of the MAF. But I still seem to be drawing a blank on why an air filter getting dirty is such a bad thing, regardless of mileage. It's one thing to say it isn't cost effective, but ht edebate here seems to be it gets too dirty too fast, which seems silly to me. If that dirt was in the intake tract anyway and the cotton/oil filter is dirtier than a paper one, well I would say that is empirical evidence the cotton one is filtering better.


An air filter getting dirty is not a bad thing. Air filters get dirty. The fact that the oil is what traps the dirt and it will at some point need to be cleaned is where the problem lies. I'll get to that in a bit. 



NBrehm said:


> I mean X did you find a lot of dust and dirt in the intake tract of your car after removing the K&N? I've run K&N and dry flow cotton air filters for years and I have never had an inkling of issues with dirt getting past it into the intake tract.


I didn't check for dust and dirt. This was not my filter; it was Terry's filter, so he could answer that question. 

I have run K&N intakes before and I have found dust in the intake tract but it has been long enough to where I don't know if that was the filter's fault or something else. I have had to clean MAF sensors before due to the oil. No matter, I don't need to wipe my intake down with a dry rag to know that the vast majority of used oil analysis results that come back with K&N filters installed show significantly elevated levels of silicone. The only exception I was able to find was a guy who went out of his way to claim that his UOA had no silicone on several blogs and forums. Sounded more like a K&N rep or dealer to me. If I can measure it in the oil, there's too much getting through. It's that simple.


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