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Synthetic Oil
| Synthetic oil is a lubricant consisting of chemical compounds which 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 it generally provides superior mechanical and chemical
properties than those found in traditional mineral oils. Aircraft turbines, for
example, require the use of synthetic oils, whereas aircraft piston engines
don't. History of Synthetic engine oil
Types of Synthetics
Synthetic Base Stocks, Semi-synthetic oil, Other base stocks help
semi-synthetic lubricants
Performance - Advantages and Disadvantages |
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History of Synthetic Engine Oil
Dr. Hermann Zorn of I.G. Farben Industries 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,
polyolesters, and banana oil. During the same time period in the United States,
Dr. W.A. Zisman working at the U.S. Naval Research Laboratory (NRL) was also
synthesizing esters, especially diesters.
The first real synthetic engine oils appeared for aircraft engines in World War
II concurrently in Germany and in the United States. The motivation in Germany
may be primarily related 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 synthethic oils make engine starting in winter easier
and significantly decrease soot deposits in the oil radiator, the US Air Force
adopted polyglycols (polypropylene glycol monobutylethers) beginning in March
1944.
Synthetic engine oil
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 polyolefin (PAO)
Group IV base stocks, some of which are used for automotive synthetic motor
oils.
Although used in the aviation and aerospace industries beginning in the early
1950s, the first synthetic oil developed for automotive combustion engines and
fully recognized by the American Petroleum Institute (API) was produced by the
Hatco Corp. in 1972 as per specific specification requirements by Albert J.
Amatuzio, current President and CEO of Amsoil Inc. This first API-rated
synthetic motor oil was distributed exclusively through Amsoil Inc., meeting API
(SE/CC) specifications and was based on a 10W-40 grade Diester API (category V)
formulation. Today Amsoil Inc. markets a full line of API (category IV) licensed
synthetic motor oil and many other API (category IV) PAO-base oil formulations
that are claimed by Amsoil to meet or exceed current API requirements.
Other early synthetic motor oils marketed included "The Original Syn!" by
SynLube in 1969, NEO Oil Company (formally EON) in 1970; they were dibasic acide
esters, or diesters, and polyol ester-based synthetic lubricants. In 1971
All-Proof and Mobil 1, introduced to North America in 1974 a 5W-20
grade(category IV) PAO-base oil.
Types of Synthetic Oil
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, 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 which perform much like polyalphaolefin. Group
III base stocks are considered synthetic motor oil only in the United States;
elsewhere they are not allowed to be marketed as "synthetic".
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 which have synthetic base stocks even lower 30%, high performance
additive packs consisting of esters can also be considered as synthetic
lubricants. Ratio of the synthetic base stock is generally 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,
ester and/or Group IV polyalphaolefins in order to formulate semi-synthetic
based lubricants. Group III base oils are sometimes considered as 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.
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. Even though they are considered a synthetic product they are
still mineral base stocks and counted as the mineral part of all semi-synthetic
lubricants. Group III base stocks [with certain amount of mixture of PAOs and
esters and Group V] 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. Within the US, there are no official
specifications, or standards as to which oils can be marketed as "synthetic".
Performance
Advantages
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
- Longer engine life
Disadvantages
The disadvantages of synthetic motor oils include:
- 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).
- Synthetics do not hold lead in suspension as well as mineral oil, thus
caution is advised when the engine is run on leaded fuel. As an example,
leaded fuel is still commonly used in aviation (avgas).
- 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 mineral 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."
- Synthetic oils are not recommended in automotive rotary engines.
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