I know little about oil, but from what i've gathered here and elsewhere there are only a very few oils that are true synthetics. Most oils labeled "full synthetic" like castrol are just dino with additives that allow them to call it synthetic. So what then is blend? I know when you're talking about true synthetic, blend means 1/2 dino and and half synthetic. But when the "synthetic" oil such as castrol synthetic is actually dino oil in the first place, what is thier blend? It can't be 1/2 dino and 1/2 synth because it's already all dino with additives. Please explain this to me.