Sure, new oil lower HTHS oil may be fine for engines that were designed with that oil in mind. Ye those oils are not optimal in engine that require better protection at high operating temperatures. Sure, you can't compare driving 130 mph (high load due to air resistance) for half an hour or longer to cruising at 70 mph. I think that's why most drivers can get away with using lower HTHS oil in Nort America, as long as they don't track the car. Just ask yourself, why do European and Japanese makers routinely specify different viscosities and in other parts of the world? I'd rather use the oil my engine was designed for.
[ January 13, 2004, 05:30 PM: Message edited by: moribundman ]