Had the oil filter laying around from last years break in, stripped it and had a look see. Only I forgot what to , or what not to see. As usual a search doesn't help. What I found was a very few tiny pieces of non magnetic metal looking like aluminum. And some magnetic tiny particles. What should it look like? I put the magnet to a piece of main bearing and it was magnetic, but so is the iron cylinder liner. So, I suspect this material is probably seen after a ring job?