Originally Posted By: mechanicx
We are calculating beta ratio the same way just you are using 2/20 as the beta ratio at 15/31 microns, respectively. I am assuming 2/20 means beta 2 at 20 microns. You are assuming 2/20=15/31 mean beta 2 @ 15 microns and beta 20 @ 31 microns. That would make sense but WIX claims this filter is a 21 micron nominal filter, suggesting it is beta 2 at ~20 microns.
If they were calculating it your way then the filter would be a 15 micron nominal filter. Also it wouldn't make sense that the filter is only 95% efficient at 31 microns yet 50% efficient at 15 microns although it is possible.
To find which way is correct would require contacting WIX. But evenb using your higher number 50% @ 15 microns and 95% @ 31 microns is still very low efficiency, lower than any other filter.
Purolator said most all of their filters have the same efficiency, and it makes sense since they are using the same type of media. A P1 is a 11 micron nominal filter. Which is much better than a WIX 21 micron nominal filtr which is the worst I've seen.
Gotcha, but I am using the beta ratio calculation that is from Wix's guidance. There is information and a couple slideshow screenshots from Wix on deciphering beta ratios on the link I posted earlier.
And again, I'm not suggesting that one filter is better than another; however, there's a little bit more digging to be done. I don't know if they are both doing MPE to the same SAE tests, and even if they are, there are no standards in SAE tests to derive mean pore flow. So a company could advertise 99% efficiency at 20 microns with a particular filter if they find a way to run the test to give those results. Also, I managed to get 440,000 miles on my last vehicle without ever using a PureOne. In my opinion, a lot of the flashy claims are just marketing tools.
Now all that being said, I'm not trying to defame any filters here. I like PureOnes... and Wix... and a few select other brands. Just buy what makes you feel good. They'll all do well.