So your saying not to use a K&N with the mopar air cleaner? Should I just run like a Fram in it instead. I actually took off my cold air intake and put the stock air box back on it with the tube and Im running spectra air filter. I didnt notice any difference from going from cold air intake back to stock

 

Some folks are concerned that K&N filters don't filter as effectively as a paper filter. The K&N is rated about 97% particulate whereas the paper filters claim 99%. I've run a K&N for probably 80,000 of the 110,000 or so miles on my truck with no ill effects, but it is possible that the extra 2% of particulates that get by could cause added wear on the rings and bore walls. The only way to know for certain is to run 2 theoretically identical engines thru the exact same life cycles as see which failed first and for what reason. At last check about 12,000 miles ago, I had between 173-182 psi on all cylinders, so I feel reasonably safe using the K&N filter. I think oil changes as regular intervals are more important with the K&N, and most people just don't like the mess of cleaning and oiling the filter. I will say the K&N filter got much dirtier in an open style setup, than the current setup I run.

 

There's two reasons I went back to paper with the Mopar assembly.

First, K&N doesn't make a filter that fits it perfectly. The Mopar filter assembly requires a filter that is 12.75" in diameter. K&N's closest fit are 13" and 12.5" diameter filters. So you have to run the 12.5" (the 13" will pop out), and it just doesn't look that good. With paper filters though, Purolater, Fram (though I refuse to use Fram), and others make a filter that is exactly the right size.

The second reason is the filtering. When I switched from the K&N back to paper, there was a drastically noticeable difference in the amount of fine dust and debris that was on my TB. Having noticed no performance difference between the paper and the K&N, I opted for the cleaner setup.

I do have to change the filter about twice a year or so versus K&N that can just be cleaned, oiled, and reused. So long term, paper will probably cost me more, but i'm ok with that.

 

I don't use K&N filters mainly because of the insanely high price for what seems like ****e for any type of performance gains.