Disagree. In gasoline engines that have regular oil changes the oil should stay a nice yellow-clear color for the first 1000 miles, at least. Even after 3,000 miles the oil in my car was light brown, not nearly black. The only time I saw black oil come out of a gasoline engine was in a (slightly) mis-timed motorcycle engine where, at 10,000 rpm or so, the valves had made sweet sweet love with the pistons.