K&N Air Filters

[axxiom]

I've had a K&N air filter in my Legacy for the past 25000 miles, installed at 15000 miles. I can't say, definitively, that I've noticed any improvement in gas mileage or power, but, so far, I've noticed no problems.

I've read some tests claiming to demonstrate that more dirt particles pass through the K&N filter element than with other filters.

I've also read of and talked to people claiming to have used K&N air filters for as long as 200,000 miles in their cars without problems.

Can anyone point to evidence that these air filters actually cause or contribute to reduced engine life/greater engine wear?

I know that some people believe they do, but I'm looking for actual evidence, something more than just people's opinions.

Is anyone aware of any contemplated or pending legal action against K&N for issues around their filters? I would think that since K&N air filters have been around for a number of years and selling many thousands of them, something concrete would have shown up by now regarding causality between their filter use and engine damage.

I'm not at all committed to using a K&N air filter, but if there's, in fact, no hard evidence of problems, I'll probably just keep using it, cleaning and reoiling it at 50,000 mile intervals.

[mattocs]

I took mine out. It did nothing, and I did not want to risk my engine. I use Purolator filters (air, oil, and fuel.) They are cheap and work well.

 

I don't have any personal experience with negitive effects of the K&N...but I don't want to risk it.

[1 Lucky Texan]

I don't think anyone could quantify any decrease in engine lifespan. At least, not any that could be directly attributed to the filter. There have been reports of increased silicon (read dust) in some used oil analyses - but no one seems to know if the actual particle size is detrimental to the bearing surfaces.

 

 

There HAVE been people who destroyed MAF sensors with oiled filters - be careful not to 'over' oil it. (does your car have a MAF?)

[Jim Davis]

For what it is worth, I think most off road racing teams seem to prefer the K&N to deal with impossible dirty conditions. They seem to flow better than paper when dirty. It would probably take a lot miles to break even on the cost of paper vs the reusable units.

[subyrally]

i wont use anything but k&n filters in my cars

[86subaru]

k-n in all mine also , no problems ,

[idosubaru]

racing can be a bad comparison because they don't care if they have to rebuild. race teams will rebuild a motor every day or less often as funding allows.

 

i have been using K&N filters for years. bought an XT6 with 75,000 miles and ran the same K&N in it until 196,000 miles. the car was lost due to fire but was in great shape...well that's debatable, i killed the cosmetics offroading but the engine was fine. so the filter, plugs (torquemaster), wires (magnecor) all had about 125,000 miles on them. plugs and wires were trashed due to fire (drivers side). filter was fine (passengers side), bought another XT6 and dropped it in for many more miles in that car....don't recall how many i got in the second XT6 on that K&N but easily 150,000 miles on one filter i'd say. i currently have a new one in my 220,000 mile XT6 that's been in there for years....probably 100,000 miles, but i don't recall exactly when i installed it.

[Setright]

axxiom, as you can see, there is nothing to fear.

 

I have also run K&N in my cars for big mileages and no problems. The dead MAF's that Texan brought to light is probably what has started the debate again. My Legacy did 70K miles in my ownership with a K&N and MAF, and ZERO problems.

 

The K&N sacrificies a little filtration for a lot of flow gain. (3% points worse vs. a 27% point advantage). However, as mentioned, the bits that slip by are miniscule and don't cause engine wear.

 

From racing mechs I have heard that these bits DO cause increased drag in the oil and therefore cost horsepower in the long run. I change my oil every 6k miles of street driving, so I doubt I am affected by this.

[subie94]

 

now granted it's not a k&n filter,but it's similar.(cleanable) i think i paid about $50 bucks for the filter and adapter plate that was connected to the maf.

 

only thing i noticed was a diff in the sound,specially when i really got on the gas.Oooo i did end up using more gas(think i just wanted to hear the noise)

 

still own the filter,but the abs system is in the way in my 94 legacy.i'd have to modify or buy aftermarket tube.

 

thought i'd add my 2 cents.

[rweddy]

Can anyone point to evidence that these air filters actually cause or contribute to reduced engine life/greater engine wear?

I would not use them, not worth the risk imo.

Test

[subyrally]

I would not use them, not worth the risk imo.

Test

 

 

dont bloody care.

 

 

i will always use a k&N filter. if it was as detrimental as that reports states. my engine shold have locked up about 40000 miles ago. my engine atually runs better now after years of running with a k&n filter than it did when i bought the car....

[Setright]

That test is baloney.

 

 

The first graph makes the difference between 97 and 100 look ENORMOUS!

 

The authors have felt the need to manipulate their findings, and that makes me suspicious. You can't trust that test.

[jimscat]

As with most tests that I have read, I was flawed from the beginning. I was a filter for a GM product, so the GM product was better.

 

I have yet to read anything that truelly reports the findings. You would think that if the K&N was as bad as some make it out that their sales would not be what they are. The UNI is basically the same and I have never heard anyone complain about it.

[benebob]

Having run our race car through a 1/4 with no filter, and a paper filter (got rid of my K&N years ago). The car had a better 1/4 with the cheap paper there than nothing which in my book gives much more flow than any filter even a K&N. Save your money as even with cleaing they are very pricey.

[jib]

The damage aspect is way overblown, at least in my experience. My recently totaled out 1988 Saab 9000S had a K&N for 200,000 of it’s 250,000 mile life and until it started leaking out of the rear main seal, used virtually no oil, had no blow-by, perfect looking plugs, etc. The subie has been on K&N for most of it’s life and will continue this way.

 

If the K&N were going to cause a problem, it would have in the12-14 years it was on the Saab, with cleanings only every 2-4 years.

 

Particulate size is a critically overlooked aspect. A filter is designed to take out the mid to large sized particles, as the really small ones can pass through the gap between the bearings with no issues.

Jack

[rweddy]

dont bloody care.

 

 

i will always use a k&N filter. if it was as detrimental as that reports states. my engine shold have locked up about 40000 miles ago. my engine atually runs better now after years of running with a k&n filter than it did when i bought the car....

All I know is for the nominal performance gains is it worth the possible risk?

Even if it is true or not true for the very little performance gains I would not risk one in my car. I have heard many very experienced mechanics say they would never use them in their cars so I would rather spend my $$ on proven technology.

[Jim Davis]

Jumping back in the fray: One of my other vehicles is a Dodge Viper GTS. Dodge sold the GTS/ GT-2 V10 with K&N filters stock from the factory. Now, I doubt Dodge would have compromised reliability of their largest and most expensive engine ever built by them. You can bet the engines run hard. Frankly, I would be more worried about sub-standard oil filters and oil out there. Paper filters work fine and are relatively inexpensive, but start to loose flow with every mile you drive. How important is this? In everyday driving, the flow loss would be negligible. Remember, K&N is a "performance" filter. It is not the end all of performance upgrades, but works well under severe use.

[subyrally]

ive never seen any problems arise from the k&n filters. and you want proven tech, look at cars from like 40 years ago, they came with preoiled filters in almost the same style as the k&n.. hell even k&n has been around for nearly 40 years. they havent been sued outta their money and are still in full production. that seems rather well proven tech to me.....the only issues ive ever seen with the k&n filters were generally user related. like too much oil or not installing em right.

 

 

 

All I know is for the nominal performance gains is it worth the possible risk?

Even if it is true or not true for the very little performance gains I would not risk one in my car. I have heard many very experienced mechanics say they would never use them in their cars so I would rather spend my $$ on proven technology.

[soobscript]

AMSOIL makes filters. Oil-wetted foam. K&N flow with paper filtering.

[Ranger83]

As with most tests that I have read, I was flawed from the beginning. I was a filter for a GM product, so the GM product was better.

 

I have yet to read anything that truelly reports the findings. You would think that if the K&N was as bad as some make it out that their sales would not be what they are. The UNI is basically the same and I have never heard anyone complain about it.

 

K&N has done a brilliant marketing job.

 

Most of the guys who install them don't bother doing any performance testing or logging of MPG before they install them. You can't prove or disprove any performance difference.

 

Folks who spend money on "performance equipment" without testing aren't likely going to be the ones doing oil analysis. I do oil analysis but long ago decided the K&N's are a waste of money, after doing performance testing of an OEM versus no air filter on a car I used to road race. There are too many restrictions in a street-legal car to have any real impact.

 

There's a thread on legacygt.com where a Subaru 2.5l was built up successively with new headers; intake tract; computer programming; exhaust system; high flow catalytic converters; and in the final stage, high lift cams. The total peak horsepower gain was 20hp (and the cost for the full stage was $5,200).

 

So how much hp gain do you think you get with a K&N? Decals, although "ricer" offer a bigger performance increase for the money.

[MDW25gt]

I've used the same K&N in all 3 of my subie's. I like the improved throttle response. I also don't think they have a negative impact on engine life.