Ahh, I should have said "In North America", my apologizes.
I like Castrol 0W30, in fact, I use it in one of my personal cars. However, like I said, I'm not horribly comfortable with it, since Castrol seems to change their North American formulations on a whim, not to mention the shift from PAO to Group III without a drop in price, or notifying the consumer in anyway whatsoever.
I'm also hesitant to reccomend the 0w30 to the average consumer here since they will have to search quite a bit to find it in some areas, and definitely need to carefully check every bottle to weed out the Group III version.