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Ascent Filtration Testing LLC, an independent lab, ran 5 common oil filter brands through the rigorous ISO 4548-12 oil filter filtration test method. This the standard test by which all oil filters are rated using very precise (and expensive) equipment so it's not a makeshift rig in someone's garage. They also ran flow vs pressure drop testing and bubble points. I will link the videos to those tests in the second post.
The Fram Ultraguard dominated this test at >99.8% efficient even down at 15 um while nearly flowing as well as the Wix XP when new. The Royal Purple filter did really well also in the filtration testing, but not so great in flow and loading capacity. The ACDelco Gold filter did surprisingly well considering it was the only cellulose filter in the bunch. The Purolator Boss is advertised as 95% efficient @ 25 um, but it came up short of that in this test. It did okay in the pressure drop and loading capacity testing. The Wix XP was the real let down in this test. Wix rates their XP filters at 95% efficient @ 35 um, but it came well short of that in this test as it didn't even pass 90% efficient way up at 50 um. It did excellent in the flow testing, but exhibited a bypass failure in the bubble point test.
The first graph is the full efficiency range. The next two graphs are zoomed in on the high efficiency range to better show the separation of the better filters. The last one is the pressure drop with time/loading and loading capacity. Hopefully this data can help people make informed oil filter choices. Enjoy!
06-05-2021, 11:15 AM
ISO 4548-12 Oil Filter Efficiency Data 
