For anyone interested in learning a little bit about what makes a synthetic oil, synthetic, groups, and standards, here are a couple PDF's directly off of American Petroleum Institute (API) which sets the standards of the oils you buy at the auto store.

How to read the API Certification Mark
Group X base Stock
Try looking for the API License for the "special" oils you purchase.
From there, you can see if they are meeting today's service and ILSAC standards.
Here is the main search page.

How Oils are tested based on service and ILSAC standards.

I'm just using Amsoil as an example since I like to toot my horn about it. Now I'm going to ask my rep why SS oil doesn't have an API stamp, amongst other.