I was pulling into my garage today and when I parked my car, there was a faint spray of a jet black oily substance on the ground (dry). It was uniform with a pattern that looked like it was sprayed from my exhaust of my 1991 300D. I thought first that it may be oil, but my car does not use even a drop of oil and when I checked after the car sat for 10 minutes, it was right on the money. The only explanation that I could find is that my daily commute to the office is very short, it is ver cold out and on the way home from office I took the long, long way. I was driving my car very fast and perhaps this is some of the diesel crud that has been building up from all of that short driving.
What do you think?