OVERKILL, it's speculated, (which becomes lore on this lube) that it's VISOM
http://www.exxonmobil.com/UK-English/Basestocks/PDS/GLXXENBSKEMVisom.aspx
-18 PP...
http://www.exxonmobil.com/UK-English/Basestocks/PDS/GLXXENBSKEMVisom.aspx
-18 PP...