Synthetic oil is a

lubricant A lubricant (sometimes shortened to lube) is a substance that helps to reduce friction between surfaces in mutual contact, which ultimately reduces the heat generated when the surfaces move. It may also have the function of transmitting forces, t ...

consisting of chemical compounds that are artificially modified or synthesised. Synthetic lubricants can be manufactured using chemically modified

petroleum Petroleum, also known as crude oil, or simply oil, is a naturally occurring yellowish-black liquid mixture of mainly hydrocarbons, and is found in geological formations. The name ''petroleum'' covers both naturally occurring unprocessed crud ...

components rather than whole

crude oil Petroleum, also known as crude oil, or simply oil, is a naturally occurring yellowish-black liquid mixture of mainly hydrocarbons, and is found in geological formations. The name ''petroleum'' covers both naturally occurring unprocessed crude ...

, but can also be synthesized from other raw materials. The base material, however, is still overwhelmingly crude oil that is distilled and then modified physically and chemically. The actual synthesis process and composition of additives is generally a commercial trade secret and will vary among producers. Synthetic oil is used as a substitute for petroleum-refined oils when operating in extreme temperature. Aircraft

jet engine A jet engine is a type of reaction engine discharging a fast-moving jet of heated gas (usually air) that generates thrust by jet propulsion. While this broad definition can include rocket, Pump-jet, water jet, and hybrid propulsion, the term ...

s, for example, require the use of synthetic oils, whereas aircraft

piston engines A reciprocating engine, also often known as a piston engine, is typically a heat engine that uses one or more reciprocating pistons to convert high temperature and high pressure into a rotating motion. This article describes the common featu ...

do not. Synthetic oils are also used in

metal stamping Stamping (also known as pressing) is the process of placing flat sheet metal in either blank or coil form into a stamping press where a tool and die surface forms the metal into a net shape. Stamping includes a variety of sheet-metal forming ma ...

to provide environmental and other benefits when compared to conventional petroleum and animal-fat based products. These products are also referred to as "non-oil" or "oil free".

Types

Full

Some "synthetic" oil is made from Group III base stock, some from Group IV. Some from a blend of the two.

Mobil Mobil is a petroleum brand owned and operated by American oil and gas corporation ExxonMobil. The brand was formerly owned and operated by an oil and gas corporation of the same name, which itself merged with Exxon to form ExxonMobil in 1999. ...

sued

Castrol Castrol is a British oil company that markets industrial and automotive lubricants, offering a wide range of oil, greases and similar products for most lubrication applications. The name ''Castrol'' was originally just the brand name for com ...

and Castrol prevailed in showing that their Group III base stock oil was changed enough that it qualified as full synthetic. Since then

API An application programming interface (API) is a way for two or more computer programs to communicate with each other. It is a type of software interface, offering a service to other pieces of software. A document or standard that describes how ...

has removed all references to Synthetic in their documentation regarding standards. "Full synthetic" is a marketing term and is not a measurable quality.

Group IV: PAO

Poly-alpha-olefin (poly-α-olefin, PAO) is a

non-polar In chemistry, polarity is a separation of electric charge leading to a molecule or its chemical groups having an electric dipole moment, with a negatively charged end and a positively charged end. Polar molecules must contain one or more pola ...

polymer made by polymerizing an alpha-olefin. They are designated at API Group IV and are a 100% synthetic chemical compound. It is a specific type of

olefin In organic chemistry, an alkene is a hydrocarbon containing a carbon–carbon double bond. Alkene is often used as synonym of olefin, that is, any hydrocarbon containing one or more double bonds.H. Stephen Stoker (2015): General, Organic, an ...

(organic) that is used as a base stock in the production of most synthetic lubricants. An alpha-olefin (or α-olefin) is an

alkene In organic chemistry, an alkene is a hydrocarbon containing a carbon–carbon double bond. Alkene is often used as synonym of olefin, that is, any hydrocarbon containing one or more double bonds.H. Stephen Stoker (2015): General, Organic, an ...

where the carbon-carbon double bond starts at the α-carbon atom, i.e. the double bond is between the #1 and #2 carbons in the molecule.SynLube Incorporated

All About Synthetic Oil

Group V: Other Synthetics

Group V base oils are defined by

as any other type of oil other than

mineral oil Mineral oil is any of various colorless, odorless, light mixtures of higher alkanes from a mineral source, particularly a distillate of petroleum, as distinct from usually edible vegetable oils. The name 'mineral oil' by itself is imprecise, ...

s or PAO lubricants.

Ester In chemistry, an ester is a compound derived from an oxoacid (organic or inorganic) in which at least one hydroxyl group () is replaced by an alkoxy group (), as in the substitution reaction of a carboxylic acid and an alcohol. Glycerides ar ...

s are the most famous synthetics in Group V, which are 100% synthetic chemical compounds consisting of a

carbonyl In organic chemistry, a carbonyl group is a functional group composed of a carbon atom double-bonded to an oxygen atom: C=O. It is common to several classes of organic compounds, as part of many larger functional groups. A compound containing a ...

adjacent to an

ether In organic chemistry, ethers are a class of compounds that contain an ether group—an oxygen atom connected to two alkyl or aryl groups. They have the general formula , where R and R′ represent the alkyl or aryl groups. Ethers can again be c ...

linkage. They are derived by reacting an

oxoacid An oxyacid, oxoacid, or ternary acid is an acid that contains oxygen. Specifically, it is a compound that contains hydrogen, oxygen, and at least one other element, with at least one hydrogen atom bonded to oxygen that can dissociate to produce ...

with a

hydroxyl In chemistry, a hydroxy or hydroxyl group is a functional group with the chemical formula and composed of one oxygen atom covalently bonded to one hydrogen atom. In organic chemistry, alcohols and carboxylic acids contain one or more hydroxy ...

compound such as an

alcohol Alcohol most commonly refers to: * Alcohol (chemistry), an organic compound in which a hydroxyl group is bound to a carbon atom * Alcohol (drug), an intoxicant found in alcoholic drinks Alcohol may also refer to: Chemicals * Ethanol, one of sev ...

phenol Phenol (also called carbolic acid) is an aromatic organic compound with the molecular formula . It is a white crystalline solid that is volatile. The molecule consists of a phenyl group () bonded to a hydroxy group (). Mildly acidic, it req ...

. Esters are usually derived from an inorganic acid or organic acid in which at least one -OH (hydroxyl) group is replaced by an -O-alkyl (

alkoxy In chemistry, the alkoxy group is an alkyl group which is singularly bonded to oxygen; thus . The range of alkoxy groups is vast, the simplest being methoxy (). An ethoxy group () is found in the organic compound ethyl phenyl ether (, also kn ...

) group, most commonly from

carboxylic In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group () attached to an R-group. The general formula of a carboxylic acid is or , with R referring to the alkyl, alkenyl, aryl, or other group. Carboxylic ...

acids and alcohols. That is to say, esters are formed by condensing an acid with an alcohol. Many chemically different "esters" due to their polarity and usually excellent lubricity are used for various reasons as either "additives" or "base stocks" for lubricants.

=Polyalkylene Glycol (PAG) Synthetic Oil

Industrial PAG

The terms polyalkylene glycol and polyglycol are used interchangeably. Synthetic lubricants are about 4% of the lubricants market. PAGs are about 24% of the synthetic lubricants market. Ethylene is the basic raw material used to make the synthetic lubricant polyglycols oils. When ethylene and propylene react with oxygen we obtain ethylene oxide and propylene oxide, from which the polyalkylene glycols are produced by means of polymerization. Polyalkylene glycols are usually made by combining ethylene oxide (EO) and/or propylene oxide (PO) with an alcohol or water. The mixing ratio between EO and PO, plus the oxygen bonded in the chemical structure, crucially affect the behavior of polyglycols. The gear industry predominantly uses polyglycols with an EO/PO ratio of 50:50 to 60:40, which exhibit very similar behavior. The polyglycols featuring this composition are also generally referred to as water soluble polyglycols. Polyalkylene glycol base oils are formed by reacting an alcohol with one or more alkylene oxides: Propylene oxide provides water insolubility, Ethylene oxide provides water solubility.

PAG Properties

PAGs offer properties that include: high lubricity, polarity, low traction properties, high viscosity index, controlled quenching speeds, good temperature stability and low wear. They are available in both water soluble and insoluble forms.

PAG Uses

PAGs are commonly used in quenching fluids, metalworking fluids, gear oils, chain oils, food-grade lubricants and as lubricants in HFC type hydraulics and gas compressor equipment. PAG lubricants are used by the two largest U.S. air compressor OEMs in rotary screw air compressors. PAG oils of different viscosity grades (usually either ISO VG 46 or ISO VG 100) are often used as compressor lubricants for automotive air conditioning systems employing low GWP refrigerants.

PAG Advantages

PAGs are available in a wide range of viscosity grades and additive packages for a variety of uses. Some PAGs properties such as water solubility are not commonly provided by other synthetic lubricants, such as polyalphaolefins (PAO). PAGs prevent sludge and varnish from developing at high temperatures. PAGs have viscosity indexes that are higher than PAOs. In large gears, PAG lubricant yielded lower friction than PAO lubricant. PAG oils are polar, which means that an oil film easily develops upon all moving metal parts, reducing startup wear. PAGs can be highly biodegradable, particularly the water soluble PAGs. Pags perform better than in extreme weather condition.

PAG Disadvantages

PAGs are not compatible with mineral oils, most seals, paints, varnishes. Synthetic oil is more expensive than mineral oils.

PAG Seal compatibility

PAG is usually compatible with

FKM FKM is a family of fluorocarbon-based fluoroelastomer materials defined by ASTM International standard D1418, and ISO 1629, ISO standard 1629. It is commonly called fluorine rubber or fluoro-rubber. FKM is an abreveation of Fluorine Kautschuk Mate ...

fluoroelastomer materials and VMQ (vinyl methyl silicone)

Silicone rubber Silicone rubber is an elastomer (rubber-like material) composed of silicone—itself a polymer—containing silicon together with carbon, hydrogen, and oxygen. Silicone rubbers are widely used in industry, and there are multiple formulations ...

. PAG acts as a solvent and dissolves and removes the mineral grease which causes slower motions, air leaks, and can stop 4-way valves from operating. Natural rubber, Buna-N, and most regular seals are incompatible with PAG oils, especially seals coated in mineral grease. PAG oils can cause seals to shrink or swell, thus causing severe leakage or seizure of the seal. Pneumatic air cylinders and 4-ways valves commonly use Buna-N rubber seals that coated in mineral grease.

Semi-synthetic oil

Semi-synthetic oils (also called "synthetic blends") are a mixture of mineral oil and synthetic oil, which are engineered to have many of the benefits of full synthetic oil without the cost. Motul introduced the first semi-synthetic

motor oil Motor oil, engine oil, or engine lubricant is any one of various substances used for the lubrication of internal combustion engines. They typically consist of base oils enhanced with various additives, particularly antiwear additives, deterg ...

in 1966. Lubricants that have synthetic base stocks even lower than 30% but with high-performance additives consisting of esters can also be considered synthetic lubricants. In general, the ratio of the synthetic base stock is used to define commodity codes among the customs declarations for tax purposes.

Other base stocks help semi-synthetic lubricants

API Group II- and API Group III-type base stocks help to formulate more economic-type semi-synthetic lubricants. API 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 API Group IV poly-alpha-olefins in order to formulate semi-synthetic-based lubricants. API Group III base oils are sometimes considered fully 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 entity. 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 and paraffins.

Performance of synthetic oil

The advantages of using synthetic motor oils include better low- and high-temperature viscosity performance at service temperature extremes, better (higher)

Viscosity Index The viscosity index (VI) is an arbitrary, unit-less measure of a fluid's change in viscosity relative to temperature change. It is mostly used to characterize the viscosity-temperature behavior of lubricating oils. The lower the VI, the more the v ...

(VI), and chemical and shear stability. This also helps in decreasing the loss due to evaporation. It serves resistance to oxidation, thermal breakdown, and

oil sludge Oil sludge or black sludge is a gel-like or semi-solid deposit inside an internal combustion engine, that can create a catastrophic buildup. It is often the result of contaminated engine oil and occurs when moisture and/or high heat is introduced ...

problems and extended drain intervals, with the environmental benefit of less used oil waste generated. It provides better lubrication in extreme cold conditions. The use of synthetic oils promises possibly a longer engine life with superior protection against "ash" and other deposit formation in engine hot spots (in particular in turbochargers and superchargers) for less oil burn-off and reduced chances of damaging oil passageway clogging. The performance of automobiles is improved as net increase in horsepower and torque due to less internal drag on engine. Moreover, it can improve

fuel efficiency Fuel efficiency is a form of thermal efficiency, meaning the ratio of effort to result of a process that converts chemical potential energy contained in a carrier (fuel) into kinetic energy or work. Overall fuel efficiency may vary per device, wh ...

- 1.8% to 5% has been documented in fleet tests. However, synthetic motor oils are substantially more expensive (per volume) than mineral oils and have potential decomposition problems in certain chemical environments (predominantly in industrial use).

References

{{DEFAULTSORT:Synthetic Oil Motor oils Non-petroleum based lubricants Tribology