K&N filters are bad apparently???

2002MineralGray

New Member
Feb 13, 2008
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Ok so I just put in a K&N air filter into my car. Used em for years on other various cars and bikes Ive owned. Never had a problem and was always relatively fond of K&N. Just put one in a GT for the first time. So tonight Im at work and someone at work was like "Dude K&N isnt as good as you think." so Im like "Uhhhh yeah???" and he says "yeah my buddy just came in earlier and we were talking about it, infact hes still around he'll tell ya". So this other guy (who doesn't work with us) comes walking up to the front end of the store where we were standing and hes like "Yeah the oils that K&N uses in their filters will make your mass air sensor go bad real quick. They are fine if you drive a carburated car but if its fuel injected your mass air sensor will go bad because of it." So Ive NEVER heard anything like this before so now Im here wondering if anyone has heard of this before?
 
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So are you saying my stock filter actually filtered the air better than the K&N filter than I paid $60 for? If so Im gonna be pretty pissed. hahaha.

he is correct, a brand new K&N won't filter as well as an OEM filter

i've had my K&N for 5 years (without any trouble because i'm not an idiot) and by my count, at $20 for an OEM filter once a year, i'm ahead cost-wise with years of service ahead


and word on the street is a dirty filter K&N will filter much better than a clean one. you might give up 0.073hp though
 
he is correct, a brand new K&N won't filter as well as an OEM filter
He is not correct. A brand new K&N will always out filter a new OEM filter. What it won’t do is support the same amount of flow as a brand new OEM would at that point. The advantage to the K&N is that it will consistently out filter and later outflow the OEM paper filter after a few hundred miles of regular use. And of course the fact that it’s 100% reusable.

As far as the other issue...its total Bull**** about the oil contaminating the Mass Air meter!!! I used to have the link to a video directly from K&N that particularly addressed this “myth”.

They actually purposely over oiled a filter with over 4x the required amount of oil and ran it for I don't know how many hours with not even the slightest bit of contamination. You'd literally have to submerge your filter in the stuff to contaminate it that bad to the point where it would pose a problem.

99% of the time when I see a mass air wire contaminated with oil, it’s due the small amount of blow by that gets by the rings and is sucked in through your PCV and vent tube during normal operation. The same oil that’s found in your intake tube and that works its way into the throttle body and intake manifold after several thousand miles.

Your best bet at preventing this would be to add an oil separator to the PCV line…not change your air filter!
 
So are you saying my stock filter actually filtered the air better than the K&N filter than I paid $60 for? If so Im gonna be pretty pissed. hahaha.

why do you think it lets more air through? :shrug: the dirtier (more clogged up it gets) the better it will filter, but it also won't let as much air past, and actually hurt your performance more than the stock filter.

if you keep it clean it will do fine, just don't use enough oil to let it get you meter dirty. and not a bad Idea to clean your meter with some ma cleaner after you drive it a little, after each time you clean/ re-oil your filter.
 
He is not correct. A brand new K&N will always out filter a new OEM filter. What it won’t do is support the same amount of flow as a brand new OEM would at that point. The advantage to the K&N is that it will consistently out filter and later outflow the OEM paper filter after a few hundred miles of regular use. And of course the fact that it’s 100% reusable.

As far as the other issue...its total Bull**** about the oil contaminating the Mass Air meter!!! I used to have the link to a video directly from K&N that particularly addressed this “myth”.

They actually purposely over oiled a filter with over 4x the required amount of oil and ran it for I don't know how many hours with not even the slightest bit of contamination. You'd literally have to submerge your filter in the stuff to contaminate it that bad to the point where it would pose a problem.

99% of the time when I see a mass air wire contaminated with oil, it’s due the small amount of blow by that gets by the rings and is sucked in through your PCV and vent tube during normal operation. The same oil that’s found in your intake tube and that works its way into the throttle body and intake manifold after several thousand miles.

Your best bet at preventing this would be to add an oil separator to the PCV line…not change your air filter!

I don't know if K&Ns actually cause this problem, but of course a company is going to refute/deny these kinds of claims to sell its product. BTW I don't think the mass air will be affected after just a few hours. It would take thousands of miles IMO. Maybe we should see how many miles people drive after installing a K&N and experience problems compared to other filters.
 
You're going to run into K&N haters and they'll give you those stories on why they hate them. It's always "I heard" or "My cousins brothers uncles best friend" kind of stuff. The increased air flow means reduced filtering. It depends on driving conditions, and what you expect out of the filter whether K&N is good for you.

These days, K&N filters are a flash point for debate on a lot of auto tech sites.
 
http://www.bobistheoilguy.com/airfilter/airtest3.htm

I'll let you do the reading. On a Mustang GT, the average hp gained is about 2-3 peak according to Rick Anderson's dyno.


In my nissan, I got the best mpg with the stock panel filter at 85 mph which was 33 mpg.

After switching over to a K&N conical the car definitely breathed better up top, but never again saw 33 mpg... best was 31. I switched back to the panel filter and again achieved 33 mpg but I could tell that over 5G the car didn't pull quite as hard.

Maybe I'll try a K&N on the Mustang at some point... The Notch has one.
 
even if you get a little oil on your maf you can always clean it with crc mass air cleaner only thing you can have happin is hurt a little performance,thats why crc realesed that product and they worked with dealers and aftermarket air filter companys,so mafs can be cleaned at every cleaner re oil and so performance dosent get hurt
 
To the guy that said they filter AND flow better I say no way. It can't do both. They let more air flow because they DON'T filter as well.

I considered a K&N but I pulled one out of the box and held it up to the light in the store. What I saw were holes in the filter media large enough to pass dirt. A good filter media will pass light evenly but this actually had holes that light was shinning through. No thanks!
 
To the guy that said they filter AND flow better I say no way. It can't do both. They let more air flow because they DON'T filter as well
Well...yes and no. It's true, that given two identically sized filters, the K&N will filter more, but flow less. That being said, K&N makes up for this by increasing the amount of "pleats" in the unit, thus increasing surface area of the filter which in turn will flow more air, matching or exceeding the stock filters flow characteristics.

The K&N is also constructed differently, using tightly woven cotton gauze rather than paper like the stock units. Those small perforations you’re able to see light pass through, are actually spanned by the oil in the filter. It may look like there’s nothing there to the naked eye (because for the most part, the oil is translucent), but trust me that oiled gauze is catching fare more particles of dirt than the paper unit ever will.