What most everyone misses in this debate is that the fitlers, while important, do not greatly affect the protection of an engine when the efficiency passes a minimum reasonable threshold.
The normal variation of wear rates far overshadows the residual effects of filter efficiency.
Lab testing can easily show that some filters are "better" performers than others, in both single-pass and multi-pass applications.
Real world UOA data and teardown analysis don't mimic the lab testing for two simple reasons:
1) filters are not the only thing that controls wear
2) once a satisfactory level of filtration is attained, "more" does not manifest into "better", because once a system is "clean enough" anything above that is unusable excess in a typical application
Yes - I agree that a premium filter is likely going to do a "better" job of removing particulate. But the plain fact is that most any reasonable filter is more than up to the task. While better filtration is desirable at the conceptual level, it just does not reveal itself as the greatest player on the field, when the game is actually in play.
Let me be very specific: I am not saying there isn't a difference between filter abilities; I'm saying that different filtration efficiencies don't shift the wear rates enough to be noticed in the real world. That is a very important distinction.
They ALL filter more than well enough to provide the desired outcome, and the small (minute) differences are meaningless, because normal variation is larger than the effects of the fitlers. Normal wear variance outpaces the statistical noise of filtration, when compared/contrasted fairly into a situation of the intended OEM specifications. If you don't look at this in context, and use data, your debate is just plain silly.
The topic of filtration rides alongside that of premium lubes. High-end products typically will not distinguish themselves in performance delta until the situation would manifest into a circumstance that a "normal" product were overwhelmed. If one greatly extended the OCI, then filtration would become more important. And nowhere in this debate does anyone ever acknolwedge that. And I would personally favor fitler CAPACITY over efficiency beyond the minimum threshold requirement. That makes the filter last much longer. As long as it can "clean" to a safe level, I want it to last LONGER, which improves the ROI. Most normal lubes can easily go 15k miles if the conditions are right; most normal filters can go along for that ride just as easily. Wear rates drop to practically zero after the lube anti-wear layer has been established, even when inching towards 15k miles of OCI. If the wear is at/near zero, how much "better" can a premium filter make something? You cannot improve upon "no wear" by using a "better" product!
I can show thousands of UOAs that back up my statements; I have both macro and micro data to prove it (you can start by reading over my article about UOA normalcy). I challenge anyone to show me either clinical lab or controlled real-world testing that contradicts my claim.
