Major additive company web sites usually have decent background reading. They don't have a vested interest in base oils and because they serve many oil companies, they tend not to brag.
http://www.lubrizol.com/LubeTheory/default.asp
Engine oil is 80-90% "base oil" and the rest is additives. The base oil determines most of the fluidity characteristics and some of the performance - although much of the performance in a mineral oil can approach that of a synthetic by using more additives!
Group I - Saturates < 90% and/or Sulfur >0.03% and Viscosity Index >= 80 to <120
Group II – Saturates >= 90% and Sulfur <=0.03% and Viscosity Index >= 80 to <120
Group III – Saturates >= 90% Sulfur <=0.03% and Viscosity Index >= 120
Group IV – Poly alpha olefins (PAO)
Group V – All others not included above
The confusion in the marketplace is due to a ruling that allows Group III type base oils to be called "synthetic." Gp III is about 2/3 the cost of PAO (original synthetic.) Obviously this brings a huge profit advantage when a marketer competes with a Gp III product against a Gp IV product. With so many dollars involved, the dispute goes on.
MSDS = Material Safety Data Sheet. The workplace requires it so proper treatment in case of a spill, contact, fire, hazardous condition, etc requires a quick source of information. It has evolved to include toxic material in the product, state and country legislation, and to some degree, the ingredients. As discussed above, some oil marketers simply put "engine oil" while others put the CAS (Chemical Abstract Service) number, which is very specific. My view is that when your daughter drinks it you might want the ER to have more information than "engine oil" and a toll free number to call.
The API service symbol is the round "donut" that indicates the viscosity grade, API service level, and whether it is fuel efficient or not. To use this symbol, oil marketers must license it from API. The license fee is millions of dollars for the large marketers. By licensing it, the marketer agrees to many quality standards, a blind audit, and certain testing reporting requirements. Obviously, if one says they "meet the requirements of..." but do not have the symbol, then it's sort of tagging along without having to pay or commit to all the steps.
The ILSAC Starburst is the round symbol on the front. It is a subset of the API license (you have to have the license before you can get the starburst) and it is specifically for the oils that meet the latest fuel economy and emissions compatibility requirements for new cars. It was intended as an evergreen symbol, meaning that the requirements would periodically change, and the formulations would have to be updated, but the symbol stayed the same. Kind of like a Good Housekeeping seal. The OEMs pushed for this because it allows them to instruct car owners to simply look for the symbol and not worry about viscosity or API service level. You can agree with the use of low viscosity oil / low phosphorus oil or not, but it doesn't do the consumer or industry any good when the symbol's use and meaning is not consistent.
I'm not leading to saying Amsoil is "bad" (or good) but that their marketing information needs a little explantion at times.
