Additional Testing / Information Sources
This site has actual test results on various filters. A special point of interest is the disparity in what you may read on the filter packaging for micron sizes, vs. what was actually found to be the size of particles passed by a particular filter. Even though a filter may be advertised at 10 microns, they can and do pass particles much larger than that. Hence the value of actual lab testing.
Beware of some of the other "studies" you may find on the internet where they cut apart some oil filters and make a bunch of assumptions based on what they see inside. Appearances can be deceiving. For example, just because a filter has a mile of surface area, one might be tempted to state that it is a much better filter because of the larger surface area. But if the filter material is bunched so tightly together that the pleats are touching, the filtering capability of the pleats is eliminated and the "effective" surface area has been reduced to just the outside circumference of the filter element. Flow and filtering capacity is now greatly reduced. So if you read that a particular filter is good or bad be sure it is backed up with valid testing, not just someone's opinion.
This site is a great primer for knowing what makes oil work and what happens to it over time.
Want to do a little of your own testing? Here is a test you can perform without the expense of paying an independent lab.
To compare the general flow rates of filters:
Procure a set amount of amount of oil (i.e1 gal. We recommend a single viscosity. 30w works well at around 70 degrees F), the oil filter elements to be tested, a funnel, some sort of oil catch pan and some sort of timer with a second hand.
Note: To test spin on filters you will have to carefully cut the case off of the steel filter assembly to gain access to the filter core. You may also have to do a little work to hold the filter core assembly together with the outside case missing. Be sure not to disturb the element pleats or internal support tube so that you get a fairly accurate representation of what the filter element flows as manufactured.
With the oil, the filter elements and any other items being used in the test all at the same room temperature, pour the oil through the 1st filter element and time how long it takes the entire amount to flow through filter element
Repeat the process with the subsequent filter elements and compare results (of course you'll want to include one of our reusable oil filters in this test).