Fake Oil

OK.  So I'm wondering why different brands of full synthetic oil vary in price so much.  They all say it meets the specs of a bunch of initials that probably stand for something.  And it's synthetic.  It all looks alike, and I bet it tastes alike.

I've gone with the bargain brand a couple of times and it seems OK.  I think fake oil is probably not much different from container to container, no matter what the label says.  I hope so.  If I am wrong on this, I'd rather be told now so I don't feel compelled to do oil fake oil research.