K&N Air Filter?

Adam R wrote:
If someone is getting dirt past the filter, I'd guess it was either installed wrong or the filter element was damaged.

In my case it was neither of those, just the poor filtering of the K&N. Hold a K&N up to the sun or bright light. See those holes? That's where the dust gets through.

Things might be different on a gasser too. Mine was K&N drop in panel filter in the stock housing on a turbo diesel, so at high boost that turbo was really sucking a lot of air through the filter. I discovered the dust by accident actually, I found dust in the intake tube upstream of the filter. Very fine dust, but dust all the same. To double check, I cleaned the tube with brake cleaner and a paper towel, and re-installed the K&N. I ran it that way a few more months, certain that the intake tube was 100% dust free when I started. Next time I checked it ~15,000 miles or so later, there was a fine layer of dust in it again. I dug a little deeper and found a small amount of what I can only describe as a combination of K&N filter oil and dust/dirt mixture on the leading edge of the turbo impeller too. Wish I would have taken a few pictures. That did it for me - I ditched the K&N. I rechecked everything after running a stock filter element, and there was never any dust upstream of the filter.

I'm not trying to talk you out of using one or saying "you're wrong and I'm right" kind of thing, :) just clarifying my experience with using one.