5ze-fe Oil fill cap question

• I recently checked the side of the top side of my oil fill cap facing the engine block and found a tiny copper fleck, along with a bunch of microscopic metal dust. Its kind of always been like that with the metal dust. but the copper looking flake is new. Ive had my oil tested and inspected every single time its been changed and the report has always come back as clean. I also have pulled oil out of the crankcase to check for glitter / shavings and have really never found anything worthwhile. Am i missing something? The engine is JDM and only has like 80k miles at this point. Is it because the threads act as a filter for the oil over time and that stuff naturally accumulates or am i going have to rebuild this engine. It sort of has a very light thump when it idles but a toyota tech looked at it and told me it was the ac pulley. Maybe thats the connecting rods knocking?

 

I think you will have better luck asking this question in the 1st gen forum?

https://www.tacomaworld.com/forums/1st-gen-tacomas-1995-2004.4/

 

Theres no death rattle or knocking on startup either. Maybe occasionally one of the lifters will tick once immediately after it starts but i was under the impression that was normal.

 

Of course i posted it here