Originally Posted by Hiaring8
Out of curiosity - Why do you recommend not using a K and N air filter? I am not a big "gear head engine guy" so I am very much a novice on a lot of that stuff, however I ran a K and N on my 96 Tacoma in highschool and college and never had any issues in the 90k miles I put on it during that time.

The only thing I have every heard was if you over oil them, it can set off your mass air flow sensor?

We are running an AFE dry filter on my wives 4runner.

Short: The K & N airfilters allow more abrasive particulates into your engine, and paper filters pass more than enough air so there isn't a performance penalty.

Longer: There are a lot of tests by engineers which quantify airflow, and filtering of particulates on the net.
HERE is one link

Below, is one graph (of many). This shows the dirt that got by the filter and would get in the engine, so lower is better. smile

[Linked Image]

It is rather technical (because it done by real engineers, not automotive writers or anonymous internet persons), but the graphs are good so take the time to look at the graphs (it isn't rocket surgery! grin

if you want more, google something like "test of K & N air filters" . You will find LOTS of K & N material (they market very aggressively), but disregard those and just look at the independent tests where they really measure things!

I used to use a K & N air filter, but I don't anymore because I couldn't find a quantitative test that found them to be better than conventional filters -- all the tests I found indicated the opposite. This was quite a few years ago, but I think these comparison tests are still valid.

John