In the USA, it is totally meaningless ever since some idiot judge ruled that highly refined mineral oil can be sold as synthetic. So it is pointless to debate whether an oil is fully meaningless or semi-meaningless.
The legal position on calling lubricant fluids SYNTHETIC is different in some parts of Europe and in America. Many years ago, a case was brought by Castrol Germany against BP over claims by BP that their motor oil, formulated with LHC hydro-cracked, was a SYNTHETIC oil. Castrol won the case meaning that if SYNTHETIC is claimed it must be formulated with genuine synthetic, not hydro-cracked.
Some years later-when hydro-cracked materials became widely available in the marketplace, Mobil took Castrol to court in America over the claims that their oil was a SYNTHETIC when formulated with hydro-cracked stocks. The American court ruled against Mobil & as such opened the “flood gates” for the oil industry to call hydro-cracked stocks SYNTHETIC everywhere except in Germany. Today, BP own Castrol, Esso (Exxon) own Mobil & Silkolene are owned by the German Fuchs company who use MC stocks. Therefore hydro-cracked (extra highly refined mineral stocks) can legally be defined as SYNTHETIC but not in Germany.
While SAE issues many standards that are related to Motor Oil, over 20 years ago all references and "definitions" of what constitutes a "Synthetic" lubricant were deleted from such standards. American Petroleum Institute never defined what "synthetic" is. National Advertising Division of the Council of Better Business Bureau ruled that "Synthetic" is a marketing term and that it is the responsibility of the Marketer (the one who labels and markets the oil) to define what it is.
It's much better to discuss whether an oil's base stock are hydro-cracked mineral oil, PAO, esters, etc. Equally important are the additives used. Very little of this can be learned from reading the advertising or labels.
/Rant Off/
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