Here is an example of what I'm talking about from my UOA files.
This is the example used in my UOA basis study for "normalcy".
The owner ran 5k mile OFCIs. He started out using Mobil 1 and PureOne filters, because by gosh they were the "best". He did that for the first 140k miles of the UOA cycles.
He then switched over the Mobil Clean 5000 and Purolator Classic, and ran another 135k miles.
https://www.bobistheoilguy.com/used-oil-analysis-how-to-decide-what-is-normal/
The chart below is the synopsis of the data from the "micro" study in my UOA article.
As you can see from the data, there is ZERO ability to distinguish the two sets of data from one another. There is far, far more overlap in "normal" wear than there is able to be assigned to the filter. In fact, the deck was stacked because it was not only the premium filter, but also the premium PAO lube. And yet those two products together could not alter the "normal" wear of a 5k mile OFCI.
Now, as I've said repeatedly, if the OFCI were to be greatly lengthened, it would be logical at some point to believe that the premium products would likely show a disparity in performance contrasted to the lessor items. But from all the data in my UOA basis study (more than 15,000 UOAs now), there is CLEAR evidence that wear-rates drop all the way out to 15k miles; that is were my data stops. So normal people, whom follow the OLM or IOLM, are likely to never be able to see any benefit from super duper lubes and uber efficient filters, because the NORMAL VARIATION OF DAILY USE FAR EXCEEDS THE MINIMAL NUANCE THAT THE LUBE AND FILTER CAN AFFECT.
This is one of my better examples, because it's statistically viable from a single source; it's micro data. But macro data tells the same story. In normal OFCIs, the filter you use does not produce any discernible effect on wear rates because the normal daily variation is larger than what the filter can affect. I realize it is hard to accept, but that does not make it any less true.
I fully realize that superior filters make oil cleaner. What you all seem to keep ignoring is that once oil is clean enough, making it cleaner does not get you any return on the investment. Engines don't need uber-clean oil to last well over 250k miles. This Vulcan engine was at 285k miles, and I personally saw the valve covers off a few times; there was no cleanliness difference. No wear differences. Nothing from using the Mobil 1 and PureOne made the costs payback; it was all wasted money. 140k miles of M1 and P1 made the engine not one bit cleaner and not one bit better wearing than the MC5k and a classic white can (aka tearolator).
What this data proves is that both the oil and filter were NOT the controlling entity of wear. If inputs change, and the outputs do not change, then the conclusion is that the inputs did not have effect.
Theory: finer filtration and syn lubes make for less wear via cleaner oil
Reality: finer filtration and syn lubes did not alter wear in any meaningful manner
Conclusion: finer filtration and syn lubes are not the wear-control major contributing factor; other things are more important (TCB; lack of contaminant loading; soot control of the additive package; oil film wedge; etc).
Again - this is real life data of 275k accumulated miles of 5k mile OFCIs from one vehicle that was consistently operated its entire life. This is as real as it gets. This is as well controlled as it gets in real life. The tighter filter may have kept the oil cleaner, but that cleaner oil didn't make one difference in wear control. Once it's "clean enough", making it "cleaner" does nothing. Facts don't lie.
Is cleaner oil harmful? No. Unless you count all the money you spend not getting anything back in return.
Is cleaner oil helpful? Only to a point, and then it's moot.