science

Synthetic oil

Synthetic oil is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Synthetic oil rather than just read about it. In short: Synthetic oil is a lubricant consisting of chemical compounds that are artificially modified or synthesised. Synthetic oil is used as a substitute for petroleum-refined oils when operating in extreme temperature, in metal stamping to provide environmental and other benefits, and to lubricate pendulum clocks.

Key takeaways

Synthetic oil belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Synthetic oil to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Synthetic oil from memory before moving on to harder problems.

Reference excerpt

Synthetic oil is a lubricant consisting of chemical compounds that are artificially modified or synthesised. Synthetic oil is used as a substitute for petroleum-refined oils when operating in extreme temperature, in metal stamping to provide environmental and other benefits, and to lubricate pendulum clocks. There are various types of synthetic oils. Advantages of using synthetic motor oils include better low-and high-temperature viscosity performance, better (higher) viscosity index (VI), and chemical and shear stability, while disadvantages are that synthetics are substantially more expensive (per volume) than mineral oils and have potential decomposition problems.

Description Synthetic oil lubricant comprises chemical compounds that are artificially modified or synthesised. Synthetic lubricants can be manufactured using chemically modified petroleum components rather than whole crude oil, 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.

Use Synthetic oil is used as a substitute for petroleum-refined oils when operating in extreme temperature. Aircraft jet engines, for example, require the use of synthetic oils, whereas aircraft piston engines do not. Synthetic oils are also used in metal stamping 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". A polyalcanoate synthetic oil is widely used to lubricate pendulum clocks.

Types

Full Some synthetic oils are made from Group III base stock and some from Group IV, while other synthetic oils may be a blend of the two. Mobil sued Castrol and Castrol prevailed in showing that their Group III base stock oil was changed enough that it qualified as full synthetic. Since then American Petroleum Institute (API) 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 polymer made by polymerizing an alpha-olefin. It is designated as API Group IV and is a 100% synthetic chemical compound. It is a specific type of olefin (organic) that is used as a base stock in the production of most synthetic lubricants. An alpha-olefin (or α-olefin) is an alkene 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.

Group V: Other synthetics Group V base oils are defined by API as any other type of oil other than mineral oils or PAO lubricants. Esters are the most famous synthetics in Group V, which are 100% synthetic chemical compounds consisting of a carbonyl adjacent to an ether linkage. They are derived by reacting an oxoacid with a hydroxyl compound such as an alcohol or phenol. 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) group, most commonly from carboxylic acids and alcohols. That is to say, esters are formed by condensing of 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 (EO) and propylene oxide (PO), from which the polyalkylene glycols are produced by means of polymerization. Polyalkylene glycols are usually made by combination of ethylene oxide and/or propylene oxide 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 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 global warming potential 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.

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Synthetic oil

Start with the simplest possible case. Write down what Synthetic oil claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Synthetic oil before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Synthetic oil ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Synthetic oil

In research: Synthetic oil appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Synthetic oil in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Synthetic oil is common in secondary-school and first-year university syllabi. It links to neighbouring topics Motor oils, Non-petroleum based lubricants, Tribology, so understanding it makes those chapters shorter.
In everyday life: Look for Synthetic oil outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Synthetic oil in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Synthetic oil means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Synthetic oil out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Synthetic oil in simple terms?

Why does Synthetic oil matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Synthetic oil?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Synthetic oil.