Originally Posted By: ZeeOSix
Originally Posted By: kschachn
Even filters with relatively low filtering efficiencies will capture particles eventually and within a fairly short number of passes (at least when compared to how often the oil is circulated through the filter per hour). Sure you have to have a larger number of passes to get a very high probability, but even at a lower probability it may catch the particle in a single pass.
If an oil filter ISO tests at 50% @ 20 microns it will theoretically take many more trips through the filter to clean the same dirty oil to the same cleanliness as one pass on a 99% @ 20 micron filter (example below). It's all the extra round-and-round trips of the particles through the engine that cause increased wear.
Plus, lower efficiency oil filters just can't retain much of the debris below 20 microns, which are the particles that contribute to the most engine wear. In the example below, 100 times more particles (1,000,000 vs 10,000) went through the oiling system with the 50% @ 20 microns filter, and took 5 times the trips through the filter to clean up the oil.
Well yeah you've already convinced me to the utility of using a high efficiency filter for preventing wear, we don't need to hash that out anymore. I've changed my mind on that one. But in your second example, I don't argue with the math either but just how many particles are we talking about floating around in the oil at any given point in time? My question was how a UOA with particle count would show anything of relevance, given the large number of passes that will be seen prior to the drain and analysis. I'm good on wear, but again what exactly does a particle count show as part of a UOA? Are there really millions of particles being generated in such a short period of time that due to a low efficiency filter you will see them in suspension giving you a relevant number from your analysis?