Big Jim....$300 might buy you a used nitrous system! <img src="/forums/images/graemlins/notooth.gif" alt="" />

I agree that the oiled cheesecloth type air filters do a poor job of actually filtering the air. I've seen low mile jeep engines with bores worn out from all the grit they injested through a K&N type filter. The intake manifold on one 4.0l that I replaced (at 20k miles due to only having 60 lbs compression) had 1/2" of fine oily dust inside the plenum! Improperly cleaning and over oiling these filters makes the problem worse. If you read the directions that come with the filter, you are not supposed to clean it for something like 50k miles! I suppose they want the dirt to build up and help trap the finer particles, which would probably lower the airflow back to below paper element levels, anyways. Any excess oil that is pulled through the filter also tends to collect on any mass airflow sensors (used in other brand vehicles) which throws the reading off. Any excess oil pulled through the filter into the airsteam also contains very fine grit, which acts as lapping compound on the rings and bores. Any water accidently injested in heavy rain storms or while fording will also pull grit through these filters.

You can't beat a stock type filter for actually filtering the air! The best factory filtering setup on a light duty vehicle was probably the old CJ/SJ/TJ Jeep and Chevy 6.2l diesel filters that used a oiled open cell foam wrap over a stock type paper element. The oiled foam would stop the large particles, the paper element traps the fine dust.

The stock elements on most late model Jeeps are oiled paper which works very well at filtering fine dust. AC Delco air filter elements are often factory oiled for better filtering, too.