Many have conjectured about why the same vehicles are currently spec'd for different oils, depending on which continent they are sold. Generally, the European models will require a thicker oil. Some say it's because of CAFE only, at the expense of engine wear. I think that the Europeans [and other parts of the World] have traditionally used longer oil change intervals, and the Mfrs. spec heavier oils because they know they will shear down to a thinner viscosity. It could be that simple.