For you MSDS watchers, here are some base oils and additives with CAS numbers with descriptions: NOTE: The CAS numbers listed are not all inclusive of what is out there, but are basic CAS numbers. Mineral Paraffininc Base Oil - 64742-54-7; VI of +94 to 120, any group, is a generic CAS number for paraffininc base oils; Mineral Naphthenic Base Oil - 64741-96-4; VI of ~15. Mineral Aromatic Base Oil - 64742-03-7; VI of ~185. Hydrotreated paraffininc, heavy - 64742-52-5 Hydrotreated paraffinic, light - 64742-53-6 PAO's: 68649-12-7, 68037-01-4, 163149-29-9, 151006-63-2, 151006-62-1, 151006-60-9, 157707-86-3 with VII's of +155 or greater: Some PAO Producers: Chevron Phillips Synfluid PAO 4 cSt PAO Exxon Mobil SpectraSyn 4 cSt PAO INEOS Durasyn 164 4 cSt PAO Diester - 28472-97-1; VII's average +170. Polyol Esters: 68441-94-1, Pentaerythritol ester of heptanoic and isopentanoic acids 118685-29-3, Mixed pentaerythritol esters of isononionic and heptanoic acids 77-99-6, TrimethylPropane (TMP) 68515-47-9, 1,2-Benzenedicarboxylic acid, di-C11-14-branched alkyl esters, C13-rich 91050-89-4, Fatty acids, C8-10, triesters with trimethylolpropane (TMP) VII Copolymers - 127883-08-3 Additives: ZDDP Type Adds: 68649-42-3, XXXXX-46-6. Calcium Sulfonates: 61789-86-4 Moly Dithiophosphate - 68958-92-7 or 68958-92-9 Moly Disulfide Powders - 1317-33-5 Here is what happens: EM, Chevron or Shell or whomever will come out with an oil (hydrotreated, isomerized, etc) and have it CAS registered with a different (new) number. I.E., New oils produced under a specific process may have new CAS numbers. However, CAS numbers do not necessarily equate to the specific process type. Some CAS Numbers for Group III hydrocracked hydroisomerized Group III 178603-64-0, 178603-65-1, 178603-66-2 The designation of Paraffinic, Naphthenic, or Aromatic simply describes the structure of the oil molecule. It has nothing to do with waxes, solvents, or being smelly. And let's remember that MSDS are Safety Data Sheets and do not reflect the actual formula, only what the Manf. has to declare for safety reasons.