Semi-Synthetic and Group III

[Jason8691]

From what Ive read on here, everyone agrees that most semi-synthetics contain some percentage of PAO, or esters, or some other true synthetic. But most of the ones that claim to be full synthetic are really Group III, do they not contain any true synthetic at all?

 

[bmwtechguy]

A semi-synthetic, such as Motorcraft 5w30, probably contains some Group III base oil, and the bulk of the base oil is a group II or II+. Other semi-synthetic or synthetic blends such as Schaeffers 15w40 or Amsoil 15w40 actually contain significant amounts of PAO, with the rest being a group II or II+ and probably a small amount of ester. My guess would be that most retail brands of syn-blend have little Group IV or V base oil added to the mix. Pobably mostly Group III for the synthetic content.