Follow me for a second.
The Amsoil and FE were very very close in particle counts(same filter, should be). That has to say something. Both leaking equally? Unlikely. Both performing correctly? More likely.
Now the other 3 filters that are 99% and 99+% are all over the place and worse than the boss which is a rock catcher. So are those leaking? Likely. Are they performing correctly? No per iso testing which puts them better than the boss and equal to or better than the FE.
I agree with your logic. The only difference is that the rated efficiency means that all those 4 filters (Amsoil, FE, Royal Purple, XG (aka FU)), should have single digit particle counts in the 21-38 micron range.
So even the FE is suspect as it's PC in BR testing equates to 97.3% across all particles 21 to 38 micron in size vs Amsoil's 99%.
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