I honestly don't see why you'd rather have "xx% @ 20 microns" instead of "99% @ xx microns." It makes more sense from both a scientific and pragmatic perspective to list "99% @ xx microns" because with that you're being told: "Essentially every particle this size gets filtered." From there, you can guess/estimate how much it filters at 20 microns, or any number of microns. Furthermore, the NAPA website states: "Our HD Oil Filters Feature a Cellulose/Poly Media w/ Contaminant Holding Capacity That Out Performs Many of Our Top Competitors w/ Contaminant Removal as Small as 8 Micron." Sure, it doesn't say the percentage, but my educated guess is that it filters anywhere from 35% to 50% @ 8 microns.
Originally Posted By: ZeeOSix
Because WIX has now adopted the "99% @ xx microns" statement instead of the "xx% @ 20 microns" statement. Everything seems better when it's at "99%".
Originally Posted By: Sayjac
As for the Wix/(Napa Gold), whether it's 95%@20um as the betas say or 99%@21um either works fine for me. It is the first time I've seen the latter reported though.