Synthetic oil is oil consisting of chemical compounds which were not originally present in crude oil (petroleum), but were artificially made (synthesized) from other compounds. Synthetic oil could be made to be a substitute for petroleum, or specially made to be a substitute for a lubricant oil, such as conventional (or mineral) motor oil refined from petroleum. When a synthetic oil or synthetic fuel is made as a substitute for petroleum, it is generally produced because of a shortage of petroleum or because petroleum is too expensive. When synthetic oil is used as a substitute for lubricant refined from petroleum, it generally provides superior mechanical and chemical properties than those found in traditional mineral oils.
Synthetic oil as a substitute for petroleum-based oil
One form of synthetic oil is that manufactured using the Fischer-Tropsch process
which converts carbon dioxide
, carbon monoxide
, and methane
into liquid hydrocarbons
of various forms. This process was developed and used extensively in World War II
, which had limited access to crude oil
supplies. Germany's yearly synthetic oil production reached millions of tons in 1944. It is today used in South Africa
to produce most of that country's diesel
. Dr. Hermann Zorn
of I.G. Farben
Industrie in Germany actually 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
and polyol esters
and banana oil.
Another form of synthetic oil is that produced at Syncrude sands plant in Alberta, Canada. This huge facility removes highly viscous bitumen from oil sands mined nearby, and uses a variety of processes of hydrogenation to turn it into high-quality synthetic crude oil. The Syncrude plant supplies about 14% of Canada's petroleum output. A similar plant is the smaller nearby facility owned by Suncor. See synthetic fuel.
Synthetic engine oil
In the mid 1960s Chevron
U.S.A was the first to market and produce a complete range of 100% synthetic Polyalphaolefins based lubricants, which began to be marketed as a substitute for mineral oils for engine lubrication
. Although in use in the aerospace industry for some years prior, synthetic oil first became commercially available in an American Petroleum Institute
(API)-approved formula for automobile engines when standards were formalized for synthetic based lubricants.
Other early synthetic motor oils marketed included "The Original Syn!" by SynLube in 1969, NEO Oil Company (formally EON) in 1970, which were dibasic acide esters, or diesters, and polyol esters based synthetic lubricants. In 1971 All-Proof now called Redline; followed fourth by Amsoil who packaged and resold a diester-based 10W40 grade from Hatco in 1972, and then Mobil 1, introduced in North America in 1974 (with a PAO-based 5W20 grade).
Synthetic Base Stocks
Synthetic motor oils have been made 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, alkyklated 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. The best of these perform much like polyalphaolefin. Group III base stocks are considered synthetic motor oil ONLY in the United States. . Group III based lubricants are not allowed to be marketed as "synthetic" in any market outside of the USA.
The technical advantages of synthetic motor oils include:
- Measurably better low and high temperature viscosity performance
- 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 on cold starts
The disadvantages of synthetic motor oils include:
- Initial costs are usually four times greater than petroleum-based oils, though at one time, man-made oils cost ten times more than petroleum . Initial costs are often mitigated by extended change intervals, which individuals may confirm through used oil analysis (UOA).
- The lower friction may make them unsuitable for break-in (i.e. the initial run-in period of the vehicle) where friction is desirable to cause wear. Improved engine part machining has made break-in less critical than it once was though. Many modern cars now come with synthetic oil as a factory fill.
- Potential decomposition problems in certain chemical environments (industrial use dominantly)
- Potential stress cracking of plastic components like POM (polyoxymethylene) in the presence of PAOs (polyalphaolefins).
- Potential on some older pushrod race engines with roller lifters for the roller itself not to spin with camshaft movement, but rather slide while the roller itself remains either stationary or at a lower circumferential speed than that of the camshaft lobe
- In July 1996, Consumer Reports published the results of a two year motor oil test involving a fleet of 75 New York taxi cabs and found no noticeable advantage of synthetic oil over regular oil. In their article, they noted that "Big-city cabs don't see many cold start-ups or long periods of high speed driving in extreme heat. But our test results relate to the most common type of severe service - stop-and-go city driving." According to their study, synthetic oil is "worth considering for extreme driving conditions: high ambient temperatures and high engine load, or very cold temperatures." This research was criticized by some because most engine damage appears to be caused by cold starts, and their research method may not have included enough cold starts to be representative of personal vehicle use.
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. DELPHI
introduced the first semi-synthetic motor oil in 1966.