Well well well. I decided to reach out to M+H to see if they had updated test results:
"Hello,
Can you please provide me with the most recent ISO filtration efficiency test results or specification sheets for your Purolator line of oil filters (Purolator, PurolatorONE, PurolatorBOSS, Purolator 20K)?
Thank you."
And this is what I got back
"No sir, we cannot. The only information available is what is listed on our website.
www.purolatornow.com
Thank you,
Mann+Hummel Product Information
Product Information (800) 526-4250)"
Needless to say I will be reconsidering using any M+H-made filters.