quote:
Originally posted by G-Man II:
Rotella T uses Group II and Group II+ base oils. I got this direct from an engineer at Shell.
Rotella T Synthetic uses Shell's proprietary XHVI base oil, which is a Group III, but unlike other Group IIIs, XHVI is a wax isomerate, meaning the feedstock used to produce it isn't the VGO from the distiller, but is rather slack wax or waxy raffinate. This processs produces a much purer base oil, and one with a much higher inherent VI than conventional hydrocracked Group IIIs.