There is a new trend in another forum. This is: Why not use a 4 stroke motorcycle oil in a car? The postive points should be: - Better VI improvers, more shearstable, better addtive package (meant for gear lubriaction, to - better EP additives) and generally more robust base oils and so on. In short, a high quality motorcycle oil should work well in a car that is driven hard and sporty, better than a average car oil. Especially in engines with timing chain. Or you could mix it with you car oil, to boost it up, as some kind of additive. I read often that you schould not use Motorcycle oils in cars, but if i remember correctly the reasons explained dont convince me. I am shure that most bike oils today should also be safe for use with a catalytic converter. Any thoughts or input to this?