Re: Aftermarket OE replacement air filters
I've heard all the suggestions that K&N leaves oily residue on the inside of the air tube. I just checked mine with about 28,000 on the filter and 29,000 on the car. No oily stuff anywhere.
As far as maintenance goes, it needs a little work every 50,000 miles, or about every 3-4 years the way I drive, and will outlast the car. About $50 for one air filter versus changing them for $7-$11 dollars every 25,000 miles. If I go 200,000 miles it would cost $28-$44 for paper and require no maintenance, so the K&N costs more.
As far as K&N letting sand through that paper doesn't, paper doesn't breathe like cotton does. When Mount Saint Helens blew her top back in 1980 the only vehicles driving around while the ash was in the air were ones with oil bath air cleaners. They use the same method to trap dirt that our noses do - it's captured by the oil impregnated in the cloth. Then, as the particles collect, the openings get smaller and more convoluted, causing any particles to have to change direction to make it through, something solid particles don't do as easily as air does.
I like the K&N because it makes sense to me.
For a simple dollars-and-sense, bean-counter approach, buy paper. But I feel the cloth filters better, keeping the engine cleaner and breathing better. That is not something bean counters can do well, so the value has to be made by the buyer.