Motor oil from a diesel will be very black within just a couple hundred miles, nature of the beast. I used to work on Detroit Diesels way back when and the oil was jet black in just a matter of minutes and the oil will stain big time.
My 560 on the other hand, with 181K on it, has oil the is a warm brown, about the color of tea, at 3K miles.
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.