I have never understood this blackened oil thing. My 01 stays clean for thousands of miles, my wife's libby CRD also clean for a while (egr, CCV, etc, deleted. My 06 - black as night after 30 seconds of running (literally). The 06 has all the emissions, except the piston crowns and turbine housing, removed (no third infection event, proper cam, etc.). Still, black oil. ( I am back to the stock turbo now as the top turbo in my twins, I had a GT3782 prior to that and it didn't make any difference.) I used to drive a' 82 Chevy 6.2 and it would turn the oil black as a few seconds of running. That was a naturally aspirated and NO emissions. I can't explain this at all. I know it's nothing to worry about, but it is a curiosity that I would love to know the reason. I do find the clean looking oil very reassuring however.