pjinca

The K&N filter comes pre-oiled. You only have to clean and recharge it with oil after approximately 50k miles, but I check mine at every oil change just to be sure.

@Paran - if the studies you posted are correct and the K&N performs so horribly, why are there no documented cases of an engine failure due to a K&N filter? Also, I do not always trust OEM, everyone builds to a price point. If you really think BMW did ANY testing or engineering on the air filters they put in their cars you are delusional. The winning bidder, in this case Mahle, did the engineering on the filters and provided them to BMW at an agreeable price.

paran

K&N does not perform horrbily in the amount of restricted air flow. The graph with the curve shows that is number 1. And that is K&N's claim to fame; a low resistance air filter.

That simply means that it is more porous, and allows more air/dirt to get through. The graphs show that as well. So the test looks very legit to me, and makes sense.

It is the consumers choice to decide what is more important: greater air flow or greater filtration.

K&N does not offer both, and neither does any other air filter. I chose greater filtration in-line with the route chosen by OEM car makers be it GM or BMW.

Regarding BMW testing of air filters. I have no doubt that they are trying to come as close to air fllter nirvana as possible in having both top line air filtration and air flow.

I believe that BMW does not farm everything out to subcontractors relative to performance testing. I do believe that they work with the major German filter mfg's (Mann, Mahle, Hengst, Bosch) in obtaining a product closest to their performance desires.

Yes, I have confidence in BMW, and believe that if oil based, cotton, air filters were the best, they would use them, and simply charge an air filter cleaning fee every 30k or whatever. They would still be making their money as they are a for profit enterprise.

plowery21

BMW is not voiding my warranty nor do they care Im running this filter. Not sure they believe it is a problem for their engine. Pretty sure K&N meets the specs of BMW (ie same micron as OEM) so I cant imagine how it could be worse then the paper. Not buying what paran is selling at this moment.

Also GMC never had a problem with my Banks (K&N company) ram air intake on my duramax either.

paran

A quote from the above study:

However, if a filter is using "better airflow" as their marketing tool, remember this....Does it flow better? At very high airflow volumes, probably. BUT, Our trucks CAN'T flow that much air unless super-modified, so what is the point?

The stock filter will flow MORE THAN ENOUGH AIR to give you ALL THE HORSEPOWER the engine has to give. And this remains true until the filter is dirty enough to trip the air filter life indicator.

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That is why K&N air filter users report no additional performance in their cars. And there are no independent tests that show performance increases because the stock filter provides the necessary amount of air flow to meet its performance needs.

But for those who prefer the K&N (by the way, I found the physical quality of the K&N filter to be excellent) keep this in mind about how often you clean it:



It's dirt holding capability is quite limited, so it should be cleaned more often than an OEM filter is replaced.

pcy

Not sure what's the point of debates like this one.
I am convinced [based on watching these kinds of debates for more than 20 years] that humans tend to make up their mind first and then -- accept the points that support the belief and reject the points that doesn't agree with the belief.

It's ok to disagree with the above statements :-) Every one learns... at their own pace.

:-) enjoy the ride(s). Enjoy life.

darkrider

It should come pre-oiled in a sealed plastic bag. While I don't doubt the accuracy of the test above, I would say that the assumption that OEM is better assumes that oiled filter media is allowing particles in that are big enough to damage the engine, which is simply untrue! I've been running oiled media on cars and motorcycles for years with no negative results to speak of. One of those vehicles had over 238K on it (no top-end rebuild) and was still running when I got rid of it. It had an oiled filter since 3K miles! I currently have a Dual Cone Intake (DCI) setup using custom Green filters (used on many race platforms), and I love the performance and sound on the N54 platform! Turbos love to breathe, and if there's any doubt about dirt/grit getting past the filter, it's easy enough to verify as it will hit the impeller blades on the turbo prior to getting into the engine. Folks over at e90post and n54tech have been running similar setups with 60K+ miles with no signs of turbo wear!

JWMich

I believe that unicorns live and frolic on the rainbow that ends at the holy BMW performance testing fortress of solitude. I have no doubt that is where performance nirvana exists and I have confidence that all OEM parts on all my BMWs are the best there could possibly be and cannot possibly be improved upon. Peace be unto you, my soul brother.

darkrider

While JWMich's response is cracking me up, sarcasm aside, I think it's important to note that oiled filter media actually requires more service to keep it clean, especially in dusty conditions! You use an oiled media filter because it is less restrictive and will save you money long term, not because it's easier to service! BMW's refusal to use them stock, is the same as other major manufacturers and has nothing to do with the filter quality, which is actually better than paper filters. The bottom line for OEMs is that it's easy to change out a paper filter! Anyone who has ever washed, dried and re-oiled a K&N filter or the like, knows that it's a bit of a chore. It's worth it IMO, but it all comes down to individual preference. Neither is going to make your engine last longer when used properly!

paran

It's simple science guys. A K&N air filter "breathes better" because it is more porous. That porosity, as the test illustrates, means that more dirt gets through as well. Is that extra dirt enough to kill your engine? I doubt it, but I believe it can hurt performance since it enters the combustion chamber thousands of times per minute and can begin to accumulate (I would also assume either pre- chamber or to post-chamber components) . But no doubt, a K&N filter allows more dirt into your engine with greater air flow.

You know that BMW would simply have a refab house clean, re-oil, and repackage for BMW dealers so it would also be a drop in replacement for them at the service bay. I don't think that's the reason they don't use K&N technology, I think the dirt issue is the main reason.

I have no axe to grind against K&N, as it is a free marketplace, and they offer a product to those consumers that want more air flow than what the OEM guys are willing to provide. They have been successful with that strategy and I applaud them. It is the American Way and I am proud that this country offers it.

But caveat emptor also applies to their marketing message of greater air flow.

paran

I just realized that I still have my K&N 33-2294 filter. I have no idea how many miles are on it, but I took these shots and some by holding it up to the sun:









You can have it for $20 delivered anywhere in the lower 48 states of the USA.