Towpig LQ4 with 141k miles. This was after the 5th OCI of Valvoline Restore and Protect. Each change the filter has the typical small bits of dark debris that others have photographed/videoed. Those small bits were also observed in the head.
The EGR is contaminating the intake with a lot of soot. The cathedral ports have a noticeable section on the top where the injector is washing that clean. I'll likely remedy the EGR problem, since that's not doing the engine any favors. Doesn't seem unreasonable to imagine some of the EGR contamination makes its way into the ringlands and crankcase.
Once EGR is resolved, time to walnut blast.