Difference Between Fully Synthetic and Semi Synthetic Difference Between Fully Synthetic and Semi Synthetic abramgrant (Chemical) (OP) 20 Nov 13 00:08 What is the main difference in Fully Synthetic and Semi Synthetic Engine oil ? Abram Grant: Automotive Lubricant & Motor Engine Oil: http://www.p-oil.co.kr RE: Difference Between Fully Synthetic and Semi Synthetic romke (Automotive) 20 Nov 13 08:33 the difference is in the types of basefluids that are used. a fully synthetic engine oil usually has a blend of polyalphaolefins and esters, a semi-synthetic oil also contains a certain amount of mineral baseoil and a conventional engine oil is based on mineral baseoils only. as a result of the use of different basefuids the properties of the final products will differ in terms of thermal stability, sensitivity of the viscosity to changes in temperature, solubility of additives and compatibility with elastomer materials as used in gaskets and seals. the word "synthetic" and "semi synthetic" is not defined very precise. generally speaking in the oil industry it is used as in the description above. however, as soon as the word is used in relation to metal working fluids, the meaning changes. there "semi synthetic" means containing polyalphaolefins, whereas "synthetic" means "not containing mineral baseoil and/or polyalphaolefins"..... RE: Difference Between Fully Synthetic and Semi Synthetic dgallup (Automotive) 20 Nov 13 18:10 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/ ---------------------------------------- The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows. RE: Difference Between Fully Synthetic and Semi Synthetic ivymike (Mechanical) 22 Nov 13 18:06 I just buy Mobil 1 "fully synthetic" and call it a day... RE: Difference Between Fully Synthetic and Semi Synthetic romke (Automotive) 23 Nov 13 11:32 although there are some differences as a result of various legal procedures to what may be called "synthetic" the oil industry now more or less has found a way of describing base oils in more objective terms as you can see here: http://globalindustrialsolutions.net/base-oil-defi.... the socalled "Group 3" baseoils are baseoils obtained by hydrocracking, in Europe mostly designated as "unconventional mineral baseoils" to avoid the term synthetic while at the same time being sufficiently different from baseoils belonging to Group 1 and Group 2.