The count down is dynamic, depending on how the car is used.
It starts at 14,000, but it took mine 18,000 miles before it reached zero. If it counts down fast, that would suggest a lot of short trips, or hard use, or some other operational factor.
Every engine is different. You cannot say that all Japanese engines require the same viscosity, or that just because one oil works really well in a Toyota, it will work really well in a Smart or Mitsubishi or anything else. My MX5 uses a very different oil to that which my Impreza required, even though they were both made in the same year. In fact, until you take an engine apart, you dont really know how well the oil has worked.
As Alex said, stick with the viscosity recommended by the manufacturer, or something very close to it, as its primary purpose is to protect the engine. Unless you use an oil which is completely unsuitable, or your engine is very sick, you will not notice any difference, apart from possibly a slight noise from a cold start if the oil has completely drained away from the top end since the engine stopped. In that situation, you really want the best oil possible.