That's the nature of the beast.
Every diesel I ever worked on had THE blackest dang oil. I mean, if you get this stuff on your skin, it'll stick better than red lead #5. You have to wear it off

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It was even darker if you ran the engine for another five minutes after finishing an oil change

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Good diesels and Harleys have one thing in common -
if they ain't leaking a little black oil, there's something wrong.
__________________
Mike Tangas
'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.