Acutally Castrol Syntec is a dino oil with synthetic additives. it just as synthetic as regular castrol. Mobil 1 is pretty much the same now as well. Me personally I use Mobil or Valvoline regular oil for now. My boss doesnt like use castrol at all. There heas been af ew times he told me, he would look down int he bottle and see quite a bit of ash in the bottom. And I do remember reading an online write up the contents of oils and Castrol wasnt very ranked very high at all.