Diesel oil will turn black in a second after you start it. FLUSHES? I will tell you my experience with a 1977 240D. I did a flush every 6 months. So first I drained the oil, took off the oil pan, cleaned it, then I would put in the flush and also approximately 2 quarts of pure diesel and filled the rest up with oil, started it and let it idle for no more than 3-4 minutes. Shut it off, drained the oil and again took off the pan and cleaned it again and put everything back. Lot's of shit use to come out. Filled with oil, started it and let it idle for 10 minutes before driving it. YOU MUST BE VERY CAREFUL AS YOU CAN ALSO GET METAL TO METAL FRICTION IF YOU ALLOW THIS TO RUN FOR TOO LONG AND ACTUALLY CAUSE DAMAGE.
WHAT HAPPENED TO THE CAR? Well, when I sold it, the car had a little over 500,000 miles ON THE originaL engine which was NEVER OPENED for anything and performed better than most with only 100K miles. The only maint. that was done by the pros was the valve adjustments. It was a stick and not an automatic so it was faster or at least seemed faster anyways. It was white in the beginning and then I changed its color to maroon. BTW, I had bought it with only 90K miles on it I think but I'm sure it was no more than a 100K