Just bought a 4runner after 22 years and 508k miles in my 98 XJ. Folks say the Toyota 4runner pretty solid that's why I bought it. Anyways most have the upgraded cold air intakes like k&n or trd whatever but those use reusable oiled filters that I was told those aren't good for blocking contaminants even when cleaned on the regular... sooooo basically will it harm my motor or lessen the longevity of the engines life?

  • Welcome to the site! I'm confused by your question, are you saying your reusable air filters have oil on them, or are you asking about reusable oil filters and whether they are any good?
    – GdD
    Commented Jul 1, 2020 at 7:25
  • Performance filters basically let more air through and at the same time more particulates - air is good, particulates not. There are many side by side tests around showing this. I used two oil bath filters on a V8 (filters designed for 2.25litres and V8 was 3.5l so plenty of spare capacity) it ran fine, smooth and quiet.
    – Solar Mike
    Commented Jul 1, 2020 at 8:11

1 Answer 1


Too much oil on these filters can eventually leave a small film of oil to coat the MAF sensor causing performance problems. Other than that there is no potential damage caused by these things.

  • Unless you clean and reoil the filter yourself , I doubt there will be an oil problem. I cleaned and reoiled a K&N in a Nissan Titan and never had a problem. My 1985 Nissan 350 ZX MAF went through a burn/heat cycle to clean itself, but I don't know if a modern MAF does that. Commented Jul 1, 2020 at 2:53

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