Ok, a bit of info on Synthetic..
The word Synthetic means "Man Made" (Man with upper case M means huMan)
The original Mobile 1 was a true labtory product, it was Man Made Today. I'm not sure,, I know a few years back they were saying only some of the formulas were true Synthetics.
Amzoil is a true synthetic far as I know, to this day (Checked last week).
MOST other "Synthetics" (not the quotes) are really highly refined Dino Oil.
Royal Purple..... I have not yet researched so can not comment on.
In my not very humble opinion calling an oil Synthetic, when it is really dino oil is false advertising,, Just like calling Survivor, or The Batchlor, Reality TV,,, About as real as Gilligan's Island they are.