The 41516 has a dome end bypass, in distinct opposition to the 1516. The 4xxx denotes the Wix XP vs. Gold; the Gold does have thread-end bypass. I'm not really sure where all the "stuff" came from; the oil was getting dark on the dipstick, but this OCI, like every other one I've had on this car, did not get one drop of makeup oil... so this 5.3 quarts was along for the ride for 10 months 16 days and 17,150 miles. If I was close enough to get the gunk back from Adam, I may have sent it for analysis to see what it is. We have a work account with a lab that has an SEDX microscope and can provide particle composition. That filter also sat in the garage for 5.5 months before cutting it open, so I don't know if that could affect what we see today as far as particulates?
No defending the "disliked" Wix XP/NAPA Platinum here, it is what it is... but it does give pause to those who run normal filters for 2 or 3 OCIs...