Allegedly some Japanese cars and vans have engines that are prone to sludge build-up. Is it possible that the Japanese were testing those engines in Japan, using locally available Japanese motor oil, and felt that they could safely push the envelope? But they may have been unprepared for the American motor oils. The American motor oils were unable to survive in the increased heat and formed sludge. Maybe the Japanese should import some American conventional motor oil to use when they test new engines. And maybe the Europeans should do the same thing. Put some of that ol' American dino juice in and discover that, for America, they can't push the limits.