Originally posted by sysanalyst:
The K&N filters don't filter that well. They pass many small particles that would be trapped in a "paper" filter. Another problem is that the K&N filter, being a "cloth" design, needs to be oiled to work properly. The oil leaves a film in the intake system that accumulates upon the MAF sensor elements, thus contaminating the MAF quickly.

K&N filters are good where large volumes of air flow is required, but they are not good at filtering smaller particles. I've been running them on several of my personal vehicles and have noticed several things;

* engine oil gets darker quicker
* MAF gets contaminated and requires frequent cleaning
* performance is not perceptibly better than with paper filter
* MPG hss not changed to any noticable extent

Many people swear by the K&N filters, but I swear and cuss at them.



After over a year on a K&N, my Blackstone report says, "Silicon was good at 9ppm showing good air filtration. Feel free to run the next oil 4000 miles." I haven't experienced any MAF contamination whatsoever, but I also haven't had to clean and oil the filter yet. As many other CEG'ers have said, if you don't over-oil it you shouldn't have any problems.

Since I run the universal filters and not the drop-ins, one caveat that I have experienced is heatsoak. I notice it on both vehicles, but the Sport seems to be affected more; my guess is because, among other things, with over 90000 miles its way overdue for an intake manifold cleaning. Either way, a good heatshield should mitigate most of the heatsoak effect.

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