Second thoughts about K&N

[dwasifar]

I have a 2019 Crosstrek with about 25k miles. I put in a K&N air filter when it was new and basically never looked at it again until yesterday. The car gets ordinary street and highway driving, no excessively dusty or dirty areas, and the filter didn't look super dirty when I checked it yesterday. According to K&N the cleaning interval is 50K miles, but I decided to take it out and clean it anyway. Since you have to let it dry after washing it, I put in a regular filter (Champ AF5293) for the meantime.

But.

First: the intake duct was noticeably oily. Not super-caked with oil, or anything like that, but not dry either. K&N claims these filters do not shed oil, and do not foul sensors. But it's clear to me now that they do shed oil, and although I have not had any sensor problems I can now see how that could happen.

Second: the car performs better with the paper filter. I wasn't expecting that; it surprised me. I know a new, clean K&N will have better flow-through than a stock filter, so I can only guess the 50k cleaning interval is wishful thinking and I should have cleaned it 5-10k ago.

So I'm now thinking K&N's marketing claims are not entirely credible, and I'm considering just switching back to paper filters from here on.

 

[dishdude]

K&N filters are a joke...total junk. Nothing but marketing hype. You have the visual evidence. How much dirt was in the oil trail?

 

[Dave9]

K&N lies

 

[Schandyman]

I have a 2019 Crosstrek with about 25k miles. I put in a K&N air filter when it was new and basically never looked at it again until yesterday. The car gets ordinary street and highway driving, no excessively dusty or dirty areas, and the filter didn't look super dirty when I checked it yesterday. According to K&N the cleaning interval is 50K miles, but I decided to take it out and clean it anyway. Since you have to let it dry after washing it, I put in a regular filter (Champ AF5293) for the meantime.

But.

First: the intake duct was noticeably oily. Not super-caked with oil, or anything like that, but not dry either. K&N claims these filters do not shed oil, and do not foul sensors. But it's clear to me now that they do shed oil, and although I have not had any sensor problems I can now see how that could happen.

Second: the car performs better with the paper filter. I wasn't expecting that; it surprised me. I know a new, clean K&N will have better flow-through than a stock filter, so I can only guess the 50k cleaning interval is wishful thinking and I should have cleaned it 5-10k ago.

So I'm now thinking K&N's marketing claims are not entirely credible, and I'm considering just switching back to paper filters from here on.

Stick that kn on let go.. stay with the oe style paper. Kn is a waste when it comes to air filters, their oil filters are ok to use.

 

[dwasifar]

K&N filters are a joke...total junk. Nothing but marketing hype. You have the visual evidence. How much dirt was in the oil trail?

Enough to make it gritty.

 

[dwasifar]

Stick that kn on let go.. stay with the oe style paper. Kn is a waste when it comes to air filters, their oil filters are ok to use.

I'm tending to agree with you, except for the first thing, "stick that kn on let go," which I do not understand.

 

[Schandyman]

stick that kn on let go," which I do not understand.

Sorry it's a phone app to sell or get rid of items you no longer want locally.

 

[kschachn]

Scores of long, detailed and contentious threads on this topic already. It’s a favorite of certain people.

 

[Passport1]

Lots of confirmation bias but precious few facts. Have used K&N filters on several vehicles w/o any untoward effects.

 

[RooflessVW]

Never had an issue with visible oil or dirt using a K&N or BMC.

Though I prefer aFe or AEM dry filters. Think K&N has dry filters now too.

 

[wpod]

While the K@N is out ,,toss it.

 

[Accent Abuser]

If you're dead set on a reusable filter get an AEM dry flow. Seriously though, air filters are like $15, you're not saving a meaningful amount of money by having a reusable one.

 

[B1974]

Too many people over oil the filters after cleaning them.

I'm not a fan of these things and they don't do much if anything for power and mileage, just use a good disposable filter.

 

[BISCUT]

I used them for years. I didn't notice any benefits overall. And you do have to show great care in oiling. Easy to overoil. Causing issues.

I've really had good results with the Fram Ultra Walmart exclusive long life filters in f150 and Outback. I'll stick w them.

 

[AZjeff]

So I'm now thinking K&N's marketing claims are not entirely credible, and I'm considering just switching back to paper filters from here on.

Probably one of the best maintenance choices you'll make.

 

[dwasifar]

If you're dead set on a reusable filter get an AEM dry flow. Seriously though, air filters are like $15, you're not saving a meaningful amount of money by having a reusable one.

I didn't buy it to save money; I got it for the marginal performance increase documented in this video:

 

[ZeeOSix]

I didn't buy it to save money; I got it for the marginal performance increase documented in this video:

Only more HP when basically at WOT and high RPM .... the same high air flow conditions that can make the oil on the filter (if over oiled) go downstream.

 

[dwasifar]

Lots of confirmation bias but precious few facts. Have used K&N filters on several vehicles w/o any untoward effects.

View attachment 101007

I did not have any particular expectation to confirm. In fact, if you were to expect me to have confirmation bias, you'd logically expect it to be in favor of the K&N, not against it, since I already have the money into it.

The car feeling peppier with the clean paper filter is a subjective observation, but I give it some credence because I did not expect it and was surprised when I noticed it happening.

The air duct being oily, however, is a flat fact, not an opinion. It is oily.

 

[97prizm]

K&N filters are a joke...total junk. Nothing but marketing hype. You have the visual evidence. How much dirt was in the oil trail?

K&N were developed for Baja Truck racing. Keeping the gritty sand and dirt out and keeping the engine clean enough to extend its life till the next race. Not terrible but designed for a purpose.

 

[Kuato]

Enough to make it gritty.

There is your answer. If it allows grit through, it is not good for your engine.

I used to use K&N filters also; but a few years back, maybe 12? Someone posted up some tests and evidence and I got rid of mine in a hurry.