It's the other way around. A smaller filter size will test worse than a larger sized filter of the same media in the same ISO efficiency due to the dP increasing more on the smaller filter, which causes already captured to debris to slough off the media more and go down stream. That phenomena was actually seen in all the oil filters that Ascent tested ... it's discussed in that big Ascent testing thread towards the end - see link below. This is why Purolator references their gigantic model 30001 filter in their ISO 4548-12 efficiency statement. At least Fram tests 3 different sized filters and averages their efficiency to represent that model line of filters.So, what would make a larger filter perform more poorly than a small filter, given the same media? I have seen this (size matters) posted before, but why would it make a difference? Larger surface area of the media? Higher delta p for a small filter? I realize the size Andrew tested was an XG10575, which is not really that small, in fact I use it as an oversize for GM PF48.
Would you all like to see ISO 4548-12 Oil Filter Lab Testing Comparison, Efficiency & Capacity, Pressure vs Flow, Bubble Point, and Burst?
Andrew, thank you very much for posting this. I hope this means you're feeling better. The Wix XP going longer before clogging is likely due to it letting so much through. Those results for the XP are very disappointing. It's no wonder they are shy to release the numbers.
bobistheoilguy.com