Bear in mind that one test does not provide much of an indication on way or another. It is merely a snapshot of one particular moment in time. To really be able to make a claim, you need a series of UOA with each type of filter.
Say, for example, the OCI was over a wet winter when the dust was low. Or perhaps the dust is just lower in a certain area. Also, some areas are more prone to having coarse dust,vs fine, which the K&N(or any other OCG filter) is more efficient at filtering vs an area where there is more fines in the air at which a typical OE style filter is better at filtering vs an OCG.
Also, what do we know about the "OE" filter being discussed? Is it an actual branded part from the car manufacturer, a quality replacement or a cheeseball, no name filter? Did the "OE" filter have a sealing issue? These factors, and others, can influence what you might see in UOAs. And not all cellulose filters, OE or otherwise, are created equal. Some may be no better than an OCG, or not by much.
Generally speaking, OCG filters are less efficient than cellulose or synthetic when comparing tests run on the same grade of test dust. A good OCG is still in a "safe" range either way but it delivers much better efficiency on the coarse grade of test dust. Lesser efficiency may not be much of an issue for everyone... depending on where they live and drive. Or it might be!
The thing to remember is that for the modern engine, which generally does not produce much in the way of wear metal (after break-in) or contamination internally, the air filter is the PRIMARY method of ingress for wear producing particles that both cause wear in and of themselves and create more wear particles that also cause wear. Wear begets wear and all that tends to challenge the oil more so the OCI may have to be shorter.
My thinking is if you eliminate as much of that contamination input as possible via a highly efficient filter choice, you have added to both engine and lubricant life. The way some people own, operate and maintain their engines... it may not matter much in the long term because whatever issues are created become issues for ANOTHER guy down the road. Me, I tend to keep my stuff longer .. a truck bought new in '86 and a car in 2000, so it matters.
