The di engine problem is oil vapor from blow by,use a catch can,so oil vapors will fall back to oil pan.
Yes black death occurs when maint,is not performed on injectors,new seals and cleaning.Saw one engine that top of head was caked bad.

__________________
1999 w140, quit voting to old, and to old to fight, a god damned veteran, deutschland deutschland uber alles uber alles in der welt