Originally Posted by mx5miata
the average synthetic oil with a base stock from shale mineral. If someone wanted true synthetic red line or amsoil would be the better choice. otherwise nothing wrong with NAPA, Super tech etc.
Judging by TDS and SDS from Amsoil and Redline there is quite a bit of group III in both. Also where is the benefit of a group V formulation today over a group III/IV/V blend.