My levels were miniscule. (10 ppm with an average of 35 ppm) Doesn't matter what the average is. That alone shows it's doing an excellent job filtering for my application.
Single foam flows 50% less the cotton gauss. Dual foam even less and so forth.
I have admitted foam filters dust better. Companies like K&N even sell "Pre-chargers" that fit on their filterchargers for high dust areas. As you can imagine they are made out of foam.
Another thing to think about though is filter area. Larger filter area will filter out more dust then smaller since the air flow is drawn in over a greater surface area.
BTW - Cotton gauss has been show to be between 97-99% efficient at filtering dust. You can fight over that last 1% if you like. I'll take my performance advantage every day.
Also cotton gauss filters have a service life of 25 cleanings. This is usable life, not going down to filter degradation. So that means I can use my filter for 25years (supposedly - I clean mine about once a year)
I've seen foam filters deteriorate first hand. Of course most of those were on turbo-charged cars which are a bit more demanding on the filters... (they didn't head my warnings either - turbo's do not like eating foam at 60+k rpm! - oh well)
BTW - How many Joe & Jane Schmoes that treat their car like crap using bogus filters send their oil away to be analyzed, eh? Also the info is engine specific and the Oil results are oil specific (VI, flash, etc)
Also any abnormaly high reading are not used. (like any sampling)
