Originally Posted by tallzdatank
with respect, many people run those reusable air filters for years and years without trouble. many people, myself and Jerry included, don't like them at all. they are loud, and allow a lot more dirt and water in. remember more flow of air means more flow of everything else.
I also am in the camp that doesn't really see a good purpose for a K&N on a Jeep.
I disagree that "more flow of air means more flow of everything else." This statement is, however, definitely true for a oil-bath element filter (like K&N, et al).
With K&N you're friending and fighting centrifugal force at different times (engineers smarter than me - doesn't the conservation of angular momentum have something to do with this too??). When your engine is operating at high speed, sucking a lot of air, the air flows into the filter and makes a bend into the intake tube. At high speeds the weight of the particles of dirt/dust/rust-particles-from-your-friends-frame-in-front-of-you-on-the-trail/etc. cause the particles to get stuck in the filter better. This is because the high air velocity causes the particles to have higher momentum effected by centrifugal force than the air molecules, so the particles stick to the filter and the air passes through. This is fine - it's how the filter is designed to operate.
The issue becomes you're running low engine speed in dusty climates. At low air velocity the dust is not effected the same because the forces acting upon it are lower and the dust will have a greater tendency to follow the air through the filter.
This gets worse if you don't oil the filter as often as you should or if something has caused the filter to dry out pre-maturely (high dust load, exposure to water, prolonged exposure to direct sun, etc).
If you are in a vehicle with a self-heating MAF sensor, the excess oils from the filter can cause problems by sticking to the MAF wire and causing the sensor to report resistance incorrectly leading to bad air/fuel mix (can be corrected with alcohol & a Q-tip).
If you are running a diesel engine you are more exposed to the negative side effect of low RPM dust causing problems. Diesels, which can have compression ratios from 17:1 to 21:1, when introduced to dust, sand blast the pistons/rings/turbo impeller wheel. This is called a "dust-out". It doesn't take much unfiltered dust to bring a diesel engine to its knees.
Not trying to be a negative nancy here, I just don't think they're really the greatest option for what I envision as the typical Jeep duty cycle -- UNLESS YOU JUST WANT TO!!
Jeeps are an open canvas and most of us mod them to be representative of our self expression with the machine.
I'd head to your local junk yard and grab an OE box & get the right filter --that's just me though.