OK, Forced... that's what the FSM says. And yet you know very well (you know what other place I refer to) that there are seemingly very experienced mechanics that swear by the 1-drop/20-secs method, saying it is more precise...
But my point, which I have expounded earlier, is that it cannot be "more precise," because each of those methods mentioned in this thread negates all the other ones in principle... one has to be necessarily right, if at all, and the others wrong... the question is, which one?

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1979 240D, W123, 105K miles, stick, white w/ tan interior.