I'm no chemist but I've been reading about the Ester component in a synthetic having a similar purpose to the Group I component in a dino oil. MolaKule was kind enough to tell us a great deal about esters. My understanding is additives are held in the Ester or Group I and they also provide detergency. I know some esters are for very specific uses (such as Neutra or Auto-Rx). Are there dino or Group III oils that use Esters to help with detergency? I know Maxlife has a very small amount of esters to work on seals but I suspect they are not also used as a detergent. Does Schaeffer Blend have esters? Are Esters just an expensive way to do the same job as a Group I oil? That may explain why Drive Clean blend uses group I oil.