MRED

I believe that the turbo is the culprit for the black oil. The seals/bearings on the exhaust side of the turbo allows the exhaust soot to pass into the oil as the oil passes through the turbo and back into the oil pan. If we could put an external oil supply on our Cummins that's just for the turbo then our engine oil would probably be clean/clear until at least 5000 miles and the oil for the turbo would take on the blackness.