"Oiled" Filters? What do you think?

[Jackpine]

Thought this might be a good topic of conversation - oiled filters such as K&N.

Southpaw has made his thoughts known on these in a couple of recent posts and I've been less than "charitable" about the concept of "premium" filters, like these, too, in the past.

I actually find the whole thing kind of interesting. Oiled filters used to be what you had in the very early days, and we still have them in small engines (like chainsaws, lawn mowers and weed whackers). But, in auto engines, well-designed paper, throw-away filters came into favor and replaced them.

Suddenly, though, we see the oily things being touted again as the best thing since Grandma's apple pie! Never mind the fact that if you don't oil them properly you can create a whole bunch of problems.

Seriously, what are the real advantages of the things as YOU see it? And, if you don't think much of them, why?

I'm not singling out any manufacturer here, even though I referred to K&N at the beginning. I DO think they make a "quality product", that has earned the love of a horde of faithful users.

Let's hear what YOU think!

- Jack

[Grabber523]

My thoughts:

Paper filters are effective, user friendly because you just toss the old one and throw in a new one, and very friendly to the pocketbook at the cost of being slightly more restrictive. Restriction can be beneficial in a dry filter media because the slower the air flows through the filter, the less particulate can be carried into the engine. The airflow potential of cotton gauze filters have proven time and again that power can be increased by using one in place if a paper filter, even if only slightly. One drawback of a cotton filter is that if the MAF is in close proximity of the oiled filter, there is a potential to gum up the sensor. Also, the cost of a cotton filter is a drawback. If cleaned and oiled properly and allowed to shed excess oil for several hours before reinstalling, they can be a good for a few relatively inexpensive horsepower. The way our stock air filter housing is shaped in relation to the MAF makes it relatively safe to run an oiled filter as long as the person cleaning and re-oiling the filter takes some common sense measures before reinstalling it. Do I have one? Yup. Did I notice a difference? Not really. But cotton filters come with stickers I can put on my truck! And I never have to replace it...so is one really better than the other? Nope...it's all in what you're looking for.

[ChuckD]

I think that K&N picked up on the old technology and made custom intakes for various vehicles and touted them to be the best. There wasn't anyplace really making anything custom till they came along. The issue is that people don't know how to proper care for them there for in turn do more harm than good. If you noticed that they didn't have any competitors for a few years due to their patents. Then there was a whole slew. Cotton gauze oil based filters are very good if taken car of properly. Paper filters are very good for the person that don't know jack about vehicles. Also there had been a lot of talk about people dusting turbos on diesels with the K&N. Truth be told it was by the drop in filter on the 7.3's and where the issue came from was where it sealed to the housing. After further digging, this issue itself was with the housing and how a pain in the butt it was to seal, even with the stock filter. As for advantages I think there are more shapes and designs of them compaired to a paper filter, to allow for custom applications. The key to proper filtration is proper sealing. I would almost guarrentee that a person that lost a motor and blamed the filter didn't have it installed correctly.

[soutthpaw]

Well as you already know my thoughts, They suck for modern electronic controlled gasoline engines for the simple fact that the oil seeps off the filter into the intake and attaches itself to various sensors. The thin wire or wire grid used in MAF sensor gets covered in oil and dirt and gives false readings... thus the output of the engine is only as good as the data coming into it.. A bad or fouled MAF sensor can result in poor economy, fouled plugs, carbon buildup etc...
They are fine for carbureted engines as these don't have the electronic sensor to foul up and don't use a computer to control engine operation.
As for K&N they just let too much junk through. having seen the intakes of many vehicles running K&N as well as owning a couple of vehicles that had them when I bought them I am convinced they let too much stuff in ... I could actually see right through one of them the spaces between the weave were so big....
As for small engines, That was my specialty when I worked for a John Deere dealership for a couple of years.... I have never seen such neglected equipment in my life! people buy this stuff and just run it till it dies with ZERO service or maintanence and then bring it in when it quits running... Stale, untreated fuel and 2 stroke equipment that did not have the oil added to the gasoline were the 2 most common issues... along with mower blades worn down to nubs of steel..... again these air filters would have a half inch thick layer of dirt and debris on them so oil what not even the issue... John Deere also changed it recommendation for many of the filters that required oil and now say don't oil them....

[88Racing]

My turn!

Nope don't like them unless exclusively ran at race tracks that are asphalt/concrete.
Pros:
Great in no to very little dust conditions.
The person doing the cleaning and oiling knows what they are doing.
Great on carburated race vehicles.

Cons:
Dusty dirty conditions plug them up quicker even with foam prebreather.
Over oiled the oil goes everywhere and collects and plugs with even more particles.
Under oiled more dirt into the engine.
To much hype!
Need to be fussy with their maintenance.
Around wet conditions rain sock should be used.

Stick with the paper or the "washable" dry type gauze. Dry types are cheaper and last just as long.

Lars

[MyMuddyTruck]

Well here are my 2 cents. I lived in Casa Grande, AZ. for a while. If you haven't lived there, you probably have seen it on the news where the whole town gets covered buy a dust storm. Well with winds well over 50mph blowing dust everywhere, it even gets in your house leaving the inside dusted everywhere. Now on my truck, I have a Volant cai. With all those dust storms, it gets pretty gunked up realy quick. I had thought about going back to the stock intake while I was living there. But during one of the times that I was cleaning the filter, I decided to put in a new paper filter in my wifes Honda Accord. When I looked down inside the intake tube, I saw a fine layer of dust inside the tube. There was no dust inside the intake tube of my Volant. After that, I replaced the filter on my wifes car with an oiled filter and never saw dust in there again. Granted, it was a pain cleaning them more often than most people have to but in those contitions it was worth it. Now most people don't live in conditions like that so they can get away with using paper filters. But thats just my thoughts on that.

[Jackpine]

That's a good, anecdotal bit of information, MyMuddy! Almost makes me want to run right out and buy an oily filter since it's pretty darned dusty where I live, in Tucson, too. Thanks for the input.

So far, you seem to be the only one strongly in favor of them, but I like it that you based your opinion on observed behavior, rather than "gut feel" or advertising.

- Jack

[ChuckD]

I actually have oiled filters on all my vehicles. Its just that the drop ins don't seal like a cone filter with a clamp, on mine.

[SDRANGER619]

I have a Series 77 CAI on my truck. I think the rule of thumb is to train yourself on how much oil is proper to use during a reoiling process.