I know a fellow, a mechanical engineer infact from South Africa. When he immigrated here to Canada he was in a state of shock that the recommended viscosities were so light. He also didn't understand changing the oil at 5000km, he was adament that an API SF oil was a 25,000km oil. That idea, I'm sure was not marketed in NA. His concern was engine durability, something we had difficulty comparing. One thing for sure is that nothing short of a critical fission event was going to change his ideas of what oil should be used. That's all I can say, pure heresy. But, I've wondered about these very same things for a long time.