Thanks for the encouragement guys. It's a lot of work!
Originally Posted By: EagleFTE
Wix=PuroClassic=K&N=M1. The K&N and M1 being the same is not a surprise of course. But the other two being in that group does surprise me.
I estimate the K&N, M1, WIX are also in the 98% efficiency ballpark @ 20 microns.
The 99.2% rating the M1 states gives no micron size for that %.
There seems to be a three class pattern for all the commonly available filters in all these tests. 1. Sieves, 2. 98% area, and 3. super-high efficiency.
The 98% class, as I call it, is not bad, it's a happy medium for minimum oil pressure drop for picky engines, and quite good filtration.
As I stated before, I pretty much ignore the betas that WIX puts on their website. I think tose are relics from before a switch to synthetic blend media. And as Gary Allan points out, they do not market based on efficiency ratings (and they probably don't care).
Originally Posted By: HTSS_TR
The Proline case looks cheap but it performs very well under your test conditions, specially the larger one.
I might skip the smaller one, myself, and pay the extra buck for a Purolator boxed version. Purolator Corporation is under no obligation to use their "97.5%" or "99.9%" medias to make bulk, ultra low-cost filters under other names with no reference to efficiency printed on the box.