A guy at the oil change place where I go if either I'm not doing it or not taking it to the dealer had on old pickup come in for a change. He took out the plug, and nothing happened. With a light, he could see that there was a black obstruction. He gingerly pushed a coathanger wire into the hole, worked it around a little, and presto, oil, very black oil, came dribbling through the sludge layer. Owner could not recall last change. . .