Synthetic oil is a lubricant consisting of chemical compounds that are artificially made (synthesized). Synthetic lubricants can be manufactured using chemically modified petroleum components rather than whole crude oil, but can also be synthesized from other raw materials. Synthetic oil is used as a substitute for lubricant refined from petroleum when operating in extremes of temperature, because, in general, it provides superior mechanical and chemical properties than those found in traditional mineral oils. Aircraft jet engines, for example, require the use of synthetic oils, whereas aircraft piston engines do not.
Early work 
Long before the use of petroleum oil, rendered animal fat, whale oil and vegetable oil were used as lubricants. These oils are considered synthetic oils by the modern definition because they were human-made from ingredients in the environment. It wasn't until the 1860s that petroleum oil became a popular lubricant.
In the 1930s, Dr. Hermann Zorn of I.G. Farben Industries in Germany began to search for lubricants with the properties of natural oils but without the tendencies to gel or gum when used in an engine environment. His work led to the preparation of over 3500 esters in the late 1930s and early 1940s including diesters, polyolesters, and banana oil.
During the same time period in the United States, Dr. William Albert Zismann working at the U.S. Naval Research Laboratory (NRL) was also synthesizing esters, especially diesters. Through the 1930s, Standard Oil of Indiana was also working on the extraction of synthetic feedstocks from animal fat and plant seed oil. These proved to be excellent lubricants, but could not compete on price terms with conventional oils and the research was dropped.
Aviation use 
The first real synthetic engine oils appeared for aircraft engines in World War II concurrently in Germany, the UK after research done by Rolls Royce for the Merlin and in the United States (who also used the Merlin engine). The motivation in Germany may be related primarily to resource issues, but also to functional performance requirements. The base oils for aircraft engines in Germany were based on a blend of an adipic acid ester with a poly(ethylene) oil, e.g., polymerized olefins/ethylene. Because synthetic oils made engine starting in winter easier and significantly decreased soot deposits in oil radiators, the United States Army Air Forces adopted polyglycols (polypropylene glycol monobutylethers) beginning in March 1944.
After the war, German research on synthetic oils, especially those used in jet engines, were captured by the US Army and turned over to the "big five" oil companies in the US. They largely ignored the market. Work on developing these ideas was carried on by Pete Peterson, who consulted with a number of small companies that started to supply military needs.
Automotive use 
Although used in the aviation and aerospace industries beginning in the early 1950s, automotive use took longer to start. The first semi-synthetic, consisting of a mix of mineral and synthetic oil, was released by Motul in 1966 as Century 2100. Similar blended products followed from a number of companies.
Alvin Fagan, a fighter pilot who was familiar with synthetics, started All-Proof in the late 1960s in Duluth, Minnesota to sell synthetic motor oils for use in cold weather. One of his employees, Albert Amatuzio, formed Amzoil across the Saint Louis River in Superior, Wisconsin. After being sued by Pennzoil, Amatuzio changed the company name to AMSOIL. John Williams of Pacer Petroleum filled his daughter's car with All-Proof, and was soon flooded by calls from her friends asking for it. Pacer started EON Oil to supply the demand. Exxon sued, saying that "EON" sounded too much like "Exxon", and eventually paid Pacer the fees needed to change the name, which never happened. Products from a number of these companies, a number ultimately sourced from All-Proof, were on the market in 1969 and 1970.
Another major source of early synthetic motor oils dates to research in 1944 by Italian and German companies looking for oils for jet engines. One such blend, Syn-Sol, was tested in 1953 in a Citroen 15. Further work waited until 1966, when the "Syn!" brand was launched in Italy, and later brought to North America in 1969 when the SynLube Company formed in Vancouver, BC. Sales started that year, including a sale for use on the Lunokhod 1 moon rover, and in 1971 on the US Lunar Rovers.
Motul introduced their first fully synthetic Century 300V in 1971. Other fully synthetics were released by the large US companies soon after, notably Mobil 1, a 5W-20 grade (category IV) PAO base oil introduced in 1974.
In the early 1960s, Chevron U.S.A integrated the first commercial utilization of hydrocracking technology at its Richmond California refinery. By 1993 the company introduced lubricant isodewaxing technology making Chevron one of the world's largest manufacturers of API (category II and III) base oils. Today, API (category III) base oils are marketed to the general public as fully synthetic motor oil. On July 1, 2000, Chevron Corp. combined efforts with Phillips Petroleum Co., now ConocoPhillips, to become Chevron Phillips Chemical Company, LLC. The Chevron Phillips venture is one of the top producers of polyalphaolefin (PAO) Group IV base stocks, some of which are used for automotive synthetic motor oils.
Synthetic Base Stocks 
Synthetic motor oils are man-made oils from the following classes of lubricants:
- Polyalphaolefin (PAO) = American Petroleum Institute (API) Group IV base oil
- Synthetic esters, etc. = API Group V base oils (non-PAO synthetics, including diesters, polyolesters, alklylated napthlenes, alkylated benzenes, etc.)
- Hydrocracked/Hydroisomerized = API Group III base oils. Chevron, Shell, and other petrochemical companies developed processes involving catalytic conversion of feed stocks under pressure in the presence of hydrogen into high-quality mineral lubricating oil. In 2005, production of GTL (gas-to-liquid) Group III base stocks began, best of which perform much like polyalphaolefin. Group III-base stocks are widely permitted to be marketed as synthetic motor oil with few exceptions where they are not allowed to be marketed as "synthetic" (for example, Germany).
Semi-synthetic oil 
Semi-synthetic oils (also called 'synthetic blends') are blends of mineral oil with no more than 30% synthetic oil. Designed to have many of the benefits of synthetic oil without matching the cost of pure synthetic oil. Motul introduced the first semi-synthetic motor oil in 1966.
Lubricants that have synthetic base stocks even lower 30%, high-performance additive packs consisting of esters can also be considered synthetic lubricants. In general, ratio of the synthetic base stock is used to define commodity codes among the customs declarations of tax purposes.
Other base stocks help semi-synthetic lubricants 
Group II- and Group III-type base stocks help to formulate more economic-type semi-synthetic lubricants. Group I-, II-, II+-, and III-type mineral-base oil stocks are widely used in combination with additive packages, performance packages, and ester and/or Group IV polyalphaolefins in order to formulate semi-synthetic-based lubricants. Group III base oils are sometimes considered synthetic, but they are still classified as highest-top-level mineral-base stocks. A Synthetic or Synthesized material is one that is produced by combining or building individual units into a unified entry. Synthetic base stocks as described above are man-made and tailored to have a controlled molecular structure with predictable properties, unlike mineral base oils, which are complex mixtures of naturally occurring hydrocarbons.
The technical advantages of synthetic motor oils include:
- Measurably better low- and high-temperature viscosity performance at service temperature extremes
- Better chemical & shear stability
- Decreased evaporative loss
- Resistance to oxidation, thermal breakdown, and oil sludge problems
- Extended drain intervals with the environmental benefit of less oil waste.
- Improved fuel economy in certain engine configurations.
- Better lubrication during extreme cold weather starts
- Longer engine life
- Superior protection against "ash" and other deposit formation in engine hot spots (in particular in turbochargers and superchargers) for less oil burnoff and reduced chances of damaging oil passageway clogging.
- Increased horsepower and torque due to less initial drag on engine
- Does not contain detergents
The disadvantages of synthetic motor oils include:
- Potential decomposition problems in certain chemical environments (predominantly in industrial use.)
- Because rotary engines inject small quantities of motor oil into the combustion chamber to lubricate the apex seals, and burned synthetic oil causes gummy deposits on the apex seals, synthetic oils are not recommended in automotive rotary engines.
See also 
- 3,000 mile myth
- Fischer–Tropsch process
- Mobil 1
- Red Line Oil
- Royal Purple
- Schaeffer Oil
- Synthetic fuel
- David Solomon, "Synthetic History", Nuts and Bolts, April 1992
- Eilhard Jantzen: The Origins of Synthetic Lubricants: The Work of Hermann Zorn in Germany, Part 1, Basic Studies of Lubricants and the Polymerisation of Olefins, Journal of Synthetic Lubrication, 12. 1996, Nr. 4, S. 283-301.
- H. Zorn, Chemischer Aufbau und physikalische Eigenschaften der Schmierstoffe VDI-Berichte Band 20, 1957, p. 47 ff.
- Eilhard Jantzen, "The Origins of Synthetic Lubricants: The Work of Hermann Zorn in Germany Part 2: esters and Additives for Synthetic Lubricants", Journal of Synthetic Lubrication (JSL) 13-2 (1996)
- W.A. Zismann, "Historical Review, Lubricants and Lubrication", Chapter 2 Synthetic Lubricants, 1962, pp. 6-60
- M.E. Spaght, German Aircraft Oils were made by Polymerization of Olefins Petroleum Processing, October 1946, p. 126-135
- D.K. Wilson, Fleet tests of synthetic lubricants SAE Quarterly Transactions, April 1948, Vol. 2, No. 2, p. 242-250
- C. Kratzer, D.H. Green and D.B. Williams, New synthetic lubricants SAE Journal (Transactions), Vol. 54, No. 5, May, 1946, p. 228-238
- "MOTUL History"
- "SynLube Products & Company History"
- About Us - ExxonMobil
- Distillate Hydrocracking - Handbook of Petroleum Processing
- Isodewaxing - Chevron
- DELPHI history
- ASTM Fuels & Lubricants Handbook, Hydrocarbon Chemistry, pg 169-184, section 7
- [Ref: Lubrication Fundamentals, J. George Wills, Mobil Oil Corporation]
- "Mobil rotary engine statement". Retrieved 2009-03-21.