Do some searching and you will find other posts on this topic and members best guesses many times on what groups are used in what oils.
There isn't a big difference in base oils for Dino oils. The big difference is in Syn Oils. Syn oils are mixtures of Group III, IV and V oils to meet various performance standards.
As most here will tell you. It is the additive package and how it performs in your car for your conditions that are the most important.
