I've been using Castrol 20w50. The oil pressure is 3 bar at starup and 1 bar at hot idle.

There is no knock or anything, but on startup the timing chain rattles for a few seconds. Could it be grinding on something? I can't think of a part made of copper in the chain path.

The chain was replaced about 50,000 miles ago by a shop that didn't know what they were doing. The chain rattled right after replacement. The mechanic told me the rattle will go away after a while..ha ha. I never took it back there again.

The copper particles only showed up at this oil change.