I sent an email to Larry Ludwig (he provided me with the SL/GF-3 Tech Data sheets) regarding Schaeffer's Supreme 7000 base stock and received the following reply:
Dear Mr. Raymond:
Schaeffer Mfg's Supreme 7000 engine oils are a combination of Group II plus and PAO synthetic base fluids. The Group II base stocks we use are derived from the raffinate hydrocoversion refining method. This method is one of the three types of refining methods that is used to produce Group II and Group III base stocks.
Sincerely
Lawrence G. Ludwig, Jr., OMA, CLS
Chief Chemist/Technical Director
[ August 07, 2002, 04:44 PM: Message edited by: Scott in WI ]