As said, if you want a full synthetic and to be sure there is no mineral oil, look for an oil that is made 100% from a PAO or Ester(if that exists). Otherwise you really don't know what's in it. The term full synthetic is fairly vague. I work for a company called "Hydrotex" and our oils are considered full synthetic. They are not 100% PAO, but do contian up to 10%. The primary base oil is Canadian derived group 3.