I’m doing some semi-annual auto maintenance and was going to vacuum/clean out my Toyota OEM engine air filter. But I was reading about oiled filters (e.g. K&N) and wondered if applying oil was a reasonable thing to do to my OEM filter. I think the answer is probably not, due to different densities of the material/fabric/weave used, but was still wondering if experts here felt the same.
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Not as such. OEM filters are made of paper, while oiled filters are typically cotton. The cotton is less restrictive, but it doesn’t do as good a job at capturing small particulate as paper. Hence, they use oil to catch the smaller particulates. Then you wash them out and re-oil and they last a lot longer. A paper filter element captures the particulate within the material itself, so they can’t be easily washed out.
OEM style air filters are cheap. Toyota filters average well under $30. Swap it once a year and move on.
You CAN, BUUUUT
Generally, they’re already oiled appropriately for life @ the manufacturer.
So I can’t recommend it.
(for what this is worth, my 2002 car with 219k miles on it, is on the 2nd filter; they don’t need changed that frequently in these operating conditions; YMMV, especially if you live on a dirt road, or in a dust-prone region)
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Marshall,
I’m happy to hear you are doing maintenance !
OEM air filters (the replaceable type) are very inexpensive (in most cases - I can think of a few vehicles I’ve worked on where that doesn’t apply). An “OEM” filter for your Toyota is probably closer to $10 or $15. If you (insert a reason) have to have an air filter in a Toyota branded carton, then yes $30 or more is more accurate.
Toyota does not make air filters so buying a Toyota boxed filter is not the most rational nor economical route.
I have a car with a K&N filter(clean and lightly oil), and I have a another car that just uses motor oil as a filter - oil bath like in the days of yore.
K&N /washable filters are great - but one must be cautious and not over oil them. excess oil from a washable air filter can create other issues.
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Thanks. I was reading up on this style of air filtration (pre…1960ish?) at same time I was finding out about oiled filters. Interesting history. Yeah…advice above regarding sticking with the inexpensive but disposable standard filter replacements makes most to me, I think.
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For most folks, a disposable air filter is the way to go. No mess etc.
Opinions on brands of air filters, oil filters, oil, tires, brake pads, shocks, spark plugs and everything else involving vehicle repair or maintenance will vary (of course).
A good rule to live by is to open the vehicles’s owner’s manual and actually read it and follow the scheduled maintenance in it.
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2nd the motion on the read the manual.
Have always used K&N on my cars since 1993.
Never had a problem and hardly needed to re-oil them unless I just wanted to. 
Be careful with K&N. They can cause dusting on your internal components. In my opinion it takes too much human interaction, My assumption is that if you “forget to oil” that it causes the dusting. I for one have a hard enough time remembering my last oil change.
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I’d have to say that is not the fault of the K&N filter - but the maintenance / operator / installer error.
Improper maintenance is never a good thing
I’ve installed and replaced hundreds of K&N filters on helicopters (yes helicopters) and never had an issue with a compressor blade related to a K&N filter.
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K&N is fine, and so are other brands of oiled filter, it’s just a matter of maintenance. If you don’t keep up with the maintenance, you’re screwed. That goes for anything.
Lol. Yeah that’s why I said be careful. Not blaming K&N for sure, we as people tend to get absent minded. Or there are others who procrastinate, sometimes I’m in that category, I’ll do it tomorrow.
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Tim,
You’re “normal” like most of us.
"Why do today, what we can put off until tomorrow "
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Corollary: “I might be dead tomorrow so why waste precious time today.”
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An interesting thing about K&N that I observed on a car i took out the water trap on to “reduce restriction”, the area which collected dust & debris was exactly the shape(round) of the opening in the factory air box where the air came in(which was about 3.5" away from the filter). Everything else around the circle was “clean(still red)” even after 50k kms.
Looks like a comparison of air filter, no air filter and in dire need of a filter replacement.
that’s 30k miles, American.
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Damn straight!
31k if you want to be a bit more exact. 
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I prefer “That looks about right”
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