Quote
Just for me, personally, knowing that filtration efficiency drops as the filter loads up is enough to make me want one 10k mile OCI per filter. I know the efficiency will be dropping on that 2nd OCI, and it would always be in the back of my mind. Sometimes peace of mind is worth that $9 every 12-14 months. If oil filters were $50+ each, I could see the point. They are dirt cheap though, even the "expensive" ones.
If one really looks at the now very oft posted M&H study efficiency graph, it's only very near the end when the filter is near or at it's holding capacity that any "significant" lowering of efficiency takes place. In a well maintained vehicle, you're not going to approach that area. And especially the group of people reading and posting here. For topic Ultra, even moreso with it's extended interval holding capacity. As noted here before, if you're getting near that area, you're engine has far greater issues than the fci and/or running the filter twice.
For me, like filter "flow" in pc use, filter efficiency drop off consideration, much ado about nothing.