Yeah, because my Lincoln's oil is no where NEAR that black, and it has 338,000Km on it, 12,000Km OCI's.
I'd be curious as to whether a run of M1 0w40 would clean it out a bit, maybe a run with it, with a filter change in the middle of the run, using something like a PureONE..?
Did you use M1 all that time? Which M1 are you using now?