People keep saying the difference in oil filter efficiency doesn't make any difference in engine protection or longevity, yet they have zero information to back that claim up except that "engines 'still run good' and last a long time even if you use an inefficient filter". Yet, every engine wear vs oil cleanliness study shows that cleaner oil reduced engine wear. Of course, it depends a lot on the OCI length, and as the OCI goes up so should the efficiency of the oil filter to match. Still waiting for the study that shows oil cleanliness doesn't make any difference in engine wear. Engines can be pretty worn out and "still run good".
I, for one, am a guy who says this is true in typical circumstances.
There is a distinction between a theoretical difference and a tangible difference.
Like most things, much of this depends on how we define the conditions of operation.
Ad nauseum, we've all discussed this topic.
It is a fact that there are plenty of studies that show a reduction in particulate loading results in less engine wear. Several SAE studies prove this.
It's also a fact that many of those studies are heavily manipulated HALTs (highly accelerated lifecycle test) which grossly distort conditions to purposely bring out an effect, which in reality, may well not appear in typical life conditions.
The fact that studies do show a correlation between particulate loading and wear particles in UOAs ALSO works in reverse ...
if the UOA shows no discernable difference in wear data, then the filtration didn't make a difference. You cannot have it both ways; no having your cake and eating it too. If we accept the fact that studies show finer filtration results in lower particulate loading, and correlates to less wear, then you MUST ACCEPT that if the UOA shows no statistically significant wear data difference, the "better" filter didn't avail itself above it's lessor competitor.
What folks fail to understand is that engine wear is a result of the following items working in some manner of concert with and against each other:
- OCI duration
- FCI duration
- FCI efficiency
- TCB
- engine series propensities (clean running or not, runs hot or not, design flaws or not, etc ...)
- oil grade
- oil add pack
One cannot accurately say that using a "better" (tighter) filter will ALWAYS result in less wear. That is patently untrue. It is true in some circumstances, but not all. There is plenty of data to show that short-to-moderate OCIs really don't benefit from "finer" filtration past a certain point (say 90% or greater).
Many of these discussions often surround filters which all are better than 90% efficient at 20um, and therefore the "better" filter is pretty much moot.