This is sort of an addednum to the post on the possible appearence of Domestic Castrol 0W30 .... When Green came out Molekule noted that GC had di-esters and that was part of its secrets. Someone[Terry Dyson?] however mum indicated it is similar in chemistry to Synergyn. Are their any other oils also similar? There just was something about the Green my engine liked (economy or quiet?) .... just can not scientifically prove it here I am preparing my lubro-contigency options in case Castrol pulls a switch-a-roo to Group III or a dumbed down bean counter formula. Redline,AMSOIL S2K,S3K(0&5W30) and Synergyn 3W30 are in mind.