Not to stir up anything on No Toil fans, I love the idea, but the filter oil never got "tacky" enough for me. Yes I did find enough dirt particles gone past for it to make me nervous. The filter was done correctly and oil was on for 2 days prior to the race. After the race, the surface of the filter wasn't completely filled with dirt either, but there was a lot of particles left in the airboot. Maybe I got a bad batch of the oil? I love the cleaner though! Wish it worked for my favorite filter oil! Sorry if I'm not on the bandwagon yet, remember this is just MY experience...if it works for you then stay with it.