Filter Specs

[srfdude]

When a filter specs at say, 95% at 30 microns, how many passes does that refer to? Surely not just one, otherwise in a couple minutes the oil would be sparkling clean. Since 30 microns is close to bearing clearances, at least when new, can some of those 30 get stuck in the babbit? Or is that irrelevant, and it will pass through with no consequences? I hear the various specs thrown about, and I wonder if in reality there is little difference.

 

[ZeeOSix]

Assuming it's an ISO 4548-12 efficiency, that rating is the average efficiency of the filter between new and near fully loaded conditions. In the ISO 4548-12 test, there is a particle counter upstream and down stream of the filter which continuously collects particle data. So it's basically measuring single passes through the filter on a continuous basis. Most filters will start out being most efficient when they are new, and slowly loose efficiency as they the delta-p across them increases from the debris loading. If you want to get more familiar with the ISO testing, I suggest you read this whole thread.

Would you all like to see ISO 4548-12 Oil Filter Lab Testing Comparison, Efficiency & Capacity, Pressure vs Flow, Bubble Point, and Burst?

I am thinking about running lab tests for an OEM and four aftermarket filters for testing for a Chevy truck. This testing will include ISO 4548-12 multi-pass efficiency and capacity, pressure vs flow hot and cold simulation curves, bubble point/largest pore size, and a collapse/burst test. I...

bobistheoilguy.com

Also, journal bearing clearance can be less than 30u because the journal doesn't run in the center of the journal. The slower the engine RPM, the smaller the minimum oil film thickness (MOFT) in the journal bearing. Most engine wear studies show that particles that are 20u or smaller do the most wear damage.