Originally Posted By: DGXR
I am starting to gather that higher micron numbers (40) are how filter manufacturers are creating their extended performance oil filters. For example, the Purolator Boss and Wix XP are both advertised as suitable for extended OCIs and both have higher micron ratings. There are a few exceptions (M1 EP and Bosch D+) but you pay significantly more for those.
Not all long FCI filters sacrifice efficiency for an extended change interval. Quite a few out there that are 99% at 20 microns and rated anywhere between 10k and 20k miles.
Originally Posted By: DGXR
Personally I am sticking with the Bosch Premium (filtech) and WIX standard as they are both rated 99% at 20 microns (although the Bosch has a higher holding capacity). Neither of these is advertised as suitable for extended OCI although they are very good filters and excellent value.
The regular WIX is 95% at 20 microns, not 99%