I Congreso Internacional de Ingeniería del Mantenimiento en Canarias (14 - 15 Junio)

 Los próximos días 14 y 15 de junio de 2016, TBN-Ingeniería de Mantenimiento Industrial y Servicios Integrales de Lubricación, S.L. organiza en el Palacio de Congresos Gran Canaria (INFECAR) el I CONGRESO INTERNACIONAL DE INGENIERÍA DEL MANTENIMIENTO EN CANARIAS, que será el punto de encuentro para las industrias, empresas, instituciones públicas y privadas, asociaciones de carácter nacional, regional e insular relacionadas con el mantenimiento, alumnos de ingeniería y de las escuelas de formación profesional, así como toda persona vinculada o interesada en el MANTENIMIENTO.

 Pueden visitar la página web del Congreso www.congresomantenimientocanarias.com donde podrán obtener toda la información relacionada con este evento. Es un Congreso GRATUITO, pero es importante cumplimentar la Inscripción a efectos de la adecuada organización del mismo.

 Asimismo, señalar que esta página web seguirá activa a lo largo del tiempo porque iremos dando toda la información de los cursos post congreso que se vayan ofertando, así como de los exámenes de certificación que se programen. Asimismo, estará disponible toda la actualidad relacionada con la Feria dedicada al Mantenimiento que vamos a organizar para el 2017.

 Aprovechamos la ocasión para comunicar que ya está disponible en la página de TBN- Ingeniería de Mantenimiento Industrial (www.tbn.es) el 9º Número de la REVISTA INGENIERÍA DEL MANTENIMIENTO EN CANARIAS, donde podrán visualizar todos los artículos incluidos en esta nueva edición. Esperamos que la información contenida en este nuevo número sea de su máximo interés. De igual manera, en esta web podrá encontrar todos los números anteriores de esta publicación.

Formulation of Lubricants: Additives

Base fluids generally cannot satisfy the requirements of high performance lubricants, they need additives, that are chemical compounds added to lubricating oils to improve certain of its properties to the finished oils. Usually, the amount  of additive used varies from 5 to 20%.

In addition to their beneficial effects, additives can have detrimental side effects, especially if the dosage is excessive or if interactions with other additives or with surfaces, seals and paints occur. So additives should be carefully balanced.

.Additives can be classified in three groups:

1. Lubricant Performance Enhancement Additives. Their mission is to improve base oil properties, allowing lubricant to work at extreme conditions.

a. Viscosity index (VI) improvers, long chain, high molecular weight polymers, as polymethacrylates (PMAs), poly-ethylene propylenes (OCPs), poly-styrenes-co-butadienes hydrogenated (HSDs), poly-isopropenes hydrogenated (SIPs), poly-styrenes-co-maleic-anhydride esterificated (SPE), to thicken the lubricant at elevated temperatures.

b. Pour point depressants, certain high molecular weight polymers function by inhibiting the formation of a wax crystal structure that would prevent oil flow at low temperatures, usually alkylaromatic polymers and polymethacrylates are used. A lowering of the pour point by about 11º - 17º C can be achieved.

c. Seal swell agents, promote slight swelling of seal material to counteract shrinking action of some highly paraffinic and PAO base oils. They are mainly formulated by esters.

d. Tackiness agents, are used to increase adhesiveness of lubricants on metal surfaces reducing run-off. They are formulated by high molecular weight polymers, aluminium soaps of unsaturated fatty acids.

e. Emulsifiers and demulsifiers, have the mission to emulsify water to avoid phases separation, and demulsify to separate water contamination from the lubrication system. Special polyethylene glycols and other ethoxylated substances have proved high efficiency.

2. Lubricant Protection Additives. Their mission is to protect the base oil, increasing the lubricant life.

  a. Anti-oxidants, when oil is heated in the presence of air oxidation occurs, as a result of it both the oil viscosity and the concentration of organic acids in the oil increase, and varnish and lacquer deposits may form on hot metal surfaces exposed to the oil. 

Oxidation inhibitors based in Zinc Dithiophosphate (ZDTPs), phenols compounds, diphenylamine alkylate, molybdenum and dithiocarbamate organic compounds, even sulphur and nitrogen compounds can be used; they react with the initiators, peroxy radicals, and hydroperoxides to form inactive compounds, or decompose these materials to form less reactive compounds, so they increase the live of lubricants.

  b. Metal passivators, build a passivating protective layers thus preventing the solubilization of metal ions that would work as pro-oxidants. Can be classified into three groups: film forming compounds, complex forming chelating agents and sulfur scavengers. The mostly used are benzotriazole and tolytriazole as well as their alkylated derivatives.

  c. Foam inhibitors, ability of oils to resist foaming varies considerably on type of crude oil, type and degree of refining, and viscosity, additives are formed by long chain polymers or silicones which act to destabilise surface foam.

  d. Dispersants, are chemical compounds that disperse or suspend in the oil potential sludge forming materials, joined with Detergents can delay the formation of deposits and reduce the rate at which they accumulate on metal surfaces. 

Typical dispersants are based on long chain hydrocarbons as polymeric succimides, olefin/P2S5 reaction products, polyesters, and benzylamides, that are acidified and then neutralized with compound containing basic nitrogen.

3. Metal Surface Protection Additives. Their mission is to provide active protection to metal surfaces, increasing life of equipment.

a. Anti-wear (AW), reduce friction and wear under boundary lubrication conditions; these additives form layers on the metal surface by absorption or chemisorption. They are formed by phosphorus compounds, sulfur and phosphorus compounds, sulfur and nitrogen compounds, sulfur compounds, and chlorine compounds.

b. Extreme pressure (EP), reduce friction and prevent scuffing and scoring of components operating under boundary lubrication conditions. They react with the metal surfaces producing a thin protective film in the same way of AW additives. they are formed with the same type of compounds of AW, but are much more reactive, but also passive EPs as sulfonated, especially calcium and sodium salts, and solid lubricating compounds as molybdenum disulfide. Typically EP aditives increase wear effects due their high reactivity.

c. Corrosion and rust inhibitors, there are two types of corrosion, by organic acids that develop in the oil itself, and by contaminants that are picked up and carried by the oil. Inhibitors form a protective film that prevents the corrosive materials from reaching or attacking the metal. Highly alkaline materials, as benzotriazole, substituted azoles, sulphured olefines, zinc diethyldithiophosphate, zinc diethyldithiocarbamate, trialkyl phosphites, in the oil will help to neutralize strong acids as they are formed.  

Rust inhibitors having a high polar attraction toward metal surfaces, typical materials used are amine succinates and alkaline earth sulfonates.

d. Detergents, prevent the build-up of deposits in hot running engines, joined with Dispersants. They are generally to be compound that chemically neutralize deposit precursors that form under high temperature conditions or as the result of burning fuels with high sulfur content or other materials that form acidic combustion by-products. 

   The main detergents are organic soaps and salts of alkaline earth metals such as barium, calcium, and magnesium. these materials are often referred to as metallo-organic compounds.

4. Other Additives. We can include other additives as Anti-microbial pesticide to protect lubricants from contamination, fouling or deterioration caused by bacteria, fungi, protozoa, algae, or slime; or Dyes to give a specific color type for marketing, identification or leak detection; they have no influence in lubricant performance.

Book a Free Consultation / Solicite una Consulta Gratuita

 Do you need consulting about Asset Management or Design for Reliability (D4R)? Now you can book a free consultation about the following topics:

- Asset Management (ISO 55000 / PAS-55)

- Operational Excellence, by Lean Manufacturing and TPM.

- Maintenance, Reliability and Reliability Centered Maintenance (RCM).

- Risk based Maintenance and Risk Assessment.

- Design for Reliability (D4R).

- Lubrication, Reliability Centered Lubrication.

- Failure Analysis and Forensic Engineering (Mechanical Engineering).

 Just click I Want a Free Consultation and send us an e-mail with your name, company name, some details about your consultation, and days and times you are available, so we arrange a 45 minutes meeting, by Skype, Hangouts or FaceTime, with one of our Chartered Engineers.

¿Necesita consultoría sobre Gestión de Activos o Diseño para Fiabilidad (D4R)? Ahora puede solicitar una consulta gratuita sobre los temas siguientes:

- Gestión de Activos (ISO 55000 / PAS-55)

- Excelencia Operacional, mediante Lean Manufacturing y TPM.

- Mantenimiento, Fiabilidad y Mantenimiento Centrado en Fiabilidad (RCM).

- Mantenimiento basado en Riesgo y Evaluaciones de Riesgo.

- Diseño para la Fiabilidad (D4R).

- Lubricación, Lubricación Centrada en Fiabilidad.

- Análisis de Fallos e Ingeniería Forense (Ingeniería Mecánica)

 Solamente haga click en Quiero una Consulta Gratuita y envíenos un e-mail indicando su nombre, el nombre de su compañía, detalles sobre la consulta, y su disponibilidad, para organizar una reunión de 45 minutos, por Skype, Hangouts o FaceTime, con uno de nuestros ingenieros colegiados.

Formulación de Lubricantes: Aditivos

El aceite base requiere ser mejorada con aditivos, estos son productos químicos que potencian, añaden o protegen propiedades concretas del lubricante. Su contenido puede suponer entre el 5 % y el 20 % de un aceite lubricante.

Sin embargo, los aditivos también pueden provocar efectos perjudiciales, principalmente si su contenido es demasiado elevado, si hay reacciones entre ellos o si hay reacciones con superficies metálicas, juntas o recubrimientos. Por lo que su formulación debe realizarse de forma cuidadosa.

Estos aditivos se pueden clasificar en grupos, una propuesta de clasificación es la siguiente:

1. Aditivos Mejoradores de Rendimiento. Su misión principal es mejorar las propiedades de la base, permitiendo al lubricante trabajar en condiciones más extremas. Los principales son:

a. Mejoradores del índice de viscosidad, a base de polímeros de cadena larga y alto peso molecular, como polimetacrilatos (PMAs), poli-etilen propilenos (OCPs), poli-estirenos-co-butadienos hidrogenados (HSDs), poli-isopropenos hidrogenados (SIPs), poli-estirenos-co-maleico-anhidrido esterificados (SPE) o combinación de los anteriores; que provocan una mayor viscosidad relativa a altas temperaturas que a bajas, con lo que reducen la variación de la viscosidad con la temperatura.

b. Depresores del punto de congelación, formulados con polímeros alquilaromáticos y polimetacrilatos, que ralentizan la formación de ceras que reducen la fluidez a bajas temperaturas, reduciendo el punto de fluidez entre 11º y 17º C.

c. Protectores de juntas, recubren y protegen los elastómeros aumentando la estanqueidad del sistema al provocar que esas se hinchen ligeramente, un exceso de aditivación puede ser perjudicial ya que las debilita y agrieta.

d. Mejoradores de adherencia, se utilizan para mejorar la adherencia del lubricante y ayudan a prevenir o controlar salpicaduras, goteos y fugas del lubricante. Están compuestos por largas cadenas de polímeros, similares a los utilizados como mejorador del índice de viscosidad.

e. Emulsificadores y demulsificadores, según se necesiten, ayudan a emulsionar el agua para evitar separación de fases o separan el agua al disminuir la tensión superficial. Los agentes emulsificadores suelen estar formulados con jabones metálicos, aceites de origen vegetal o animal y compuestos que modifican la polaridad.

2. Aditivos de Protección del Lubricante. Su misión principal es proteger la base, aumentando su vida útil.

  a. Antioxidantes,  la oxidación se produce en presencia de oxígeno y altas temperaturas, y da como resultado el aumento de la viscosidad del aceite y la presencia de ácidos orgánicos, lo que provoca la formación de lacas y barnices en las superficies metálicas a más altas temperaturas. 

Para retrasar la oxidación se utilizan aditivos a base de Ditiofosfato de Zinc (ZDTPs), compuestos fenólicos, alquilatos de difenilaminas, compuestos orgánicos de molibdeno y ditiocarbamatos, incluso tienen capacidad antioxidante los compuestos de azufre y nitrógeno que se pueden encontrar en el aceite base; que reaccionan con los radicales libres y los peróxidos para hacerlos inertes, de esta forma alargan la vida útil del aceite al reducir el envejecimiento.

  b. Desactivadores metálicos, forman una película inerte sobre las superficies metálicas previniendo la oxidación catalítica producida por el contacto del aceite con el metal a altas temperaturas, especialmente hierro y cobre. Se formulan a base de ácidos salicílicos, fosfóricos, acéticos, cítricos, glucónicos y lecitinas.

  c. Antiespumantes, la resistencia a la espuma dependen del tipo de base del lubricante y de su viscosidad, se utilizan aditivos a base de polímeros de sílice de cadena larga y polímeros orgánicos que anulan la formación de burbujas de aire dentro del lubricante evitando la formación de espuma.

  d. Dispersantes, su misión principal es mantener el lubricante limpio de depósitos y se utilizan en combinación con los aditivos Detergentes. Los aditivos dispersantes operan a bajas temperaturas recubriendo las partículas y evitando su crecimiento; de esta manera mantienen limpio el equipo. Están diseñados para mantener las partículas de suciedad, formadas por carbonillas y metales de desgaste, separadas lo que reduce los efectos negativos que pueden causar estos contaminantes en la viscosidad, desgaste y obturación de filtros.

Existen dos tipos, los denominados dispersantes suaves formulados a base de polímeros de éster de metacrilato de bajo peso molecular, alcoholes de cadena larga y compuestos de vinilos polares; y los denominados dispersantes sobre dimensionados (over-based) formulados con alquilos, en exceso, combinados con calcio, bario, sales de cinc, fenoles o ácidos salicílicos.

3. Aditivos de Protección de Superficies. Su misión es proteger de forma activa las superficies de los equipos, aumentando la vida útil de los componentes.

a. Antidesgaste (AW), su función principal es reducir la fricción y el desgaste en condiciones de lubricación límite, formulados a base de compuestos orgánico oxigenados, compuestos sulfurados y sulfuro-nitrogenados, ésteres organico-fosfatados, compuestos azufre-molibdeno, tricresilfosfatos (TCP) y ditiofosfatos de zinc (ZDDP); forman una película protectora en las piezas móviles que reduce la fricción, la temperatura y el contacto metal-metal a bajas velocidades y cargas elevadas.

b. Extrema presión (EP), su función es también reducir la fricción y el desgaste en condiciones de lubricación límite, principalmente bajo cargas y temperaturas elevadas, están formulados a base de dibencildisulfuros, triclorocetanos y parafinas cloradas, ceras y aceites minerales parafínicos clorados y bisulfuros de molibdeno.

c. Inhibidores de la herrumbre y de la corrosión, la corrosión puede estar provocada por ácidos orgánicos producidos por la degradación del lubricante o por contaminantes externos, se utilizan aditivos muy alcalinos que reaccionan y neutralizan los ácidos. Están formulados con fosfitos orgánicos, olefinas sulfuradas, benzotriazolos, dietilditiocarbamatos y ditiofosfatos de zinc (ZDDP). 

Los aditivos anti-herrumbre tienen una fuerte atracción polar con las superficies metálicas, que forma una película protectora que repele la humedad. Están formulados a base de sulfonatos metálicos, succinatos y otros ácidos orgánicos polares.

d. Detergentes, su misión principal es mantener el lubricante limpio de depósitos, en combinación con los aditivos Dispersantes. Están formados por una porción soluble, denominada substrato, y una porción que reacciona con la superficie metálica. El substrato está formulada a base de ácidos sulfonicos, alquilfenoles sulfitos-formaldeidos y ácidos carboxílicos y salicílicos. La porción que reacciona con las superficies metálicas está formulada, principalmente, a base de calcio, magnesio y sodio, otras formulaciones incluyen bario, litio, potasio, aluminio, zinc, plomo y estroncio. Forman una película no adhesiva sobre las superficies metálicas a alta temperatura que mantienen las partículas en suspensión.

4. Otros Aditivos. Se pueden incluir otros aditivos con funciones accesorias, como pueden ser los Colorantes que se utilizan en muy pequeñas cantidades para corregir o modificar totalmente el color del lubricante, bien por motivos de identificación del producto, imagen de marca o por requerimientos de normativa. No tienen ninguna influencia en el rendimiento.

Formulation of Lubricants: Base Oils

Base oils are the fundamental building blocks of a finished lubricating oil or grease, their properties and endurance are depending on their quality. Typically comprise 80 % - 90 % of the finished lubricant.

Every base oil meet a series of properties related to its chemical composition, the main ones are:

· Oxidation stability, degradation process by oxidative mechanisms induced by temperature.

· Thermal stability, high-temperature stability without oxygen.

· Carbon residue, solid residues formation, as soot, produced by high temperature.

· Natural solvency, capacity to solve chemical products, as additives or contaminants.

· Seal compatibility, base stocks should protect seals.

· Viscosity index, or viscosity-temperature relationship.

· Low-temperature properties, base stocks should have low wax content, because they have got a high poor point.

· Volatility, the tendency to evaporation, high volatility reduce flashpoint.

· Oxidation, corrosion, and rust, base oils should be water and acid-free.

· Colour doesn't influence the final result. Refined base oils are brown-amber colored, hydrotreated are yellow-golden colored, synthetic base oils are uncolored, and heavy-based oils are black-greenish colored.

· Toxicity, as much refined are the base oils as low toxicity they are, reaching even no toxic base oils.

· Biodegradability, high refined and synthetic base oils are practically biodegradable. The biodegradability is ensured by bio-based ester.

· Demulsification, the ability of oil and water to separate.

· Foam characteristics, the tendency to foam formation and the stability of the foam results.

1.  Mineral Base Oils.

They are manufactured from crude oil, separated by a distillation process in a vacuum column, refining in several stages and various treatments which result in a large variety of medical, cosmetic, industrial and automotive oils and lubricants.

In any case, mineral base oils are combinations of paraffin, iso-paraffin, naphthene, aromatic, and sulfur and nitrogen compounds. According to content in paraffin and iso-paraffin, base oils are called naphthenic (content in paraffinic from 42 % to 50 %), neutral (from 50 % to 56 %) and paraffinic (from 56 % to 67 %). 

Figure 1 Mineral base oils: (a) y (b) - Paraffin, (c) - Naphthene, (d) - Aromatic.

Mineral-based oils provide good lubricity and protection against corrosion, compatibility with seals and paints, natural solvency, hydrolytic stability, and low costs.

On the other hand, they have got a low flash point, high pour point, and low oxidation and temperature stability, so the range of operation temperature and duration is limited.

API (American Petroleum Institute, USA) classifies base oils by sulfur content, saturates content and viscosity index.

Usually, Group I base oils are produced by refining and dewaxing, but Group II and Group III are produced by hydrotreating, followed by dewaxing or wax isomerization. 

Base Oils	Saturates Content	Sulfur Content	Viscosity Index
Group I	<90 %	>0.03 %	80 – 120
Group II	>90 %	<0.03 %	80-120
Group III	>90 %	<0.03 %	>120

Table 1 API Clasification (1st part)

2.  Re-refined Base Oils.

Used oils content wear metals, oxidation wastes, particles from combustion, fuel, water, and anti-freeze, so the oil should be changed, but the most of molecules of base oil are in good condition and can be used again. A re-refining process eliminates contaminants and additives to blend a new lubricant.

The regeneration process starts with a chemical treatment to bind wear metals and dirt to make their elimination easier. Next, the dewatering and vacuum distillation process removes water and lighter oils. Finally, a hydrotreating process introduces hydrogen to remove sulfur, nitrogen, chlorine and oxidation products.

The process produces Group I base oils and can reach Group II base oils by high-quality hydrotreating.

3.  Gas-to-Liquids (GTL) Base Oils.

Gas-to-Liquids is a process for converting natural gas into fuels and base oils, GTL process tears natural gas molecules apart and reassembles them into longer chain molecules. The result is extremely pure base oil, formed by iso-paraffin, free of contaminants such as sulfur, aromatics, and metals; that can be considered Group III or can be transformed to Group IV.

Iso-paraffin produced by the GTL process provides good viscosity properties, oxidation resistance, and good low-temperature conditions.

4.  Synthetic Base Oils.

Synthetic base oils are produced, mainly, from low molecular weight hydrocarbons, the process produces high quality and extended service life capability base oils under extremes operating conditions.

In general terms, synthetic base oils are able to handle a wider range of application temperatures, so they provide the best protection both to high and low temperatures.

Base Oils	Type of Base
Group IV	Polyalphaolefin
Group V	Other Synthetic Bases

Table 2 API Clasification (2nd part)

The more usual synthetic base oils are:

a.  Synthetic Hydrocarbon Fluids:

The SHFs comprise the fastest-growing type of synthetic lubricant base stock, they all are compatible with mineral base stocks.

Polyalphaolefins (PAO) are unsaturated hydrocarbons with the general formula (-CH₂-)_n, free of sulfur, phosphorus, metals, and waxes. Provide excellent high-temperature stability and low-temperature fluidity, high viscosity indexes, low volatility and compatible with mineral base oils. Although the oxidation stability is lower than mineral oils and their solvency of polar additives is poor, so usually PAOs are combined with other synthetic oils.

This base oil is recommended for engine oils and gear oils.

Alkylated Aromatics formed by alkylation of an aromatic compound, usually benzene or naphthalene. Provide excellent low-temperature fluidity and low pour points, good solubility for additives, thermal stability, and lubricity. Although their viscosity index is about the same as mineral oils, they are less volatile, more stable to oxidation, high temperatures, and hydrolysis. They are used as the base of engine oils, gear oils, and hydraulic fluids.

Polybutenes are produced by controlled polymerization of butenes and isobutylenes. Compared with other synthetic base oils are more volatile, less stable to oxidation and their viscosity index is lower; their tendency to produce smoke and shoot deposits is very low so they are used to formulate 2-Stroke engine oils, also as gear oils combined with mineral or synthetic base oils.

b.  Polyalkylene Glycols (PAG):

PAG are polymers made from ethylene oxide (EO), propylene oxide (PO), or their derivatives. Solubility in water or other hydrocarbon is depending on the type of oxide.

Both provide good viscosity/temperature characteristics, low pour point, high-temperature stability, high flash point, good lubricity, good shear stability, PAGs are not corrosive for most of the metals and compatible with rubber.

The main disadvantages are low additive solvency and pour compatibility with lubricants, seals, paints, and finishes.

They are used as a base for hydraulic brake fluids (DOT3 and DOT 4) due to their water solubility, 2-Stroke engine oils due to the low deposits at high temperatures, compressor lubricants, and fire-resistance fluids.

c.  Synthetic Esters:

They are oxygen-containing compounds that result from the reaction of an alcohol with an organic acid. They have good lubricity, temperature, and hydrolytic stability, the solvency of additives and compatibility with additives and other bases. But some esters can damage seals so require special compositions.

They are used as base oils for engine oils, mixed with other synthetic bases, because they improve low-temperature properties, reduce fuel consumption, increase wear protection and viscosity-temperature properties.

Also, as 2-Stroke engine base oils, they reduce deposit formation, protecting rings, pistons, and sparks. They allow reducing the quantity of lubricant from 50:1 of mineral oils to 100:1 and up 150:1 due to their outstanding lubricity.

Phosphate Esters are used as anti-wear additives due to their high lubricity and as base oils for hydraulic fluids and compressor oils due to their low flammability. But their hydrolytic and temperature stability and viscosity index is low and their low-temperature properties are poor. Also, they are aggressive with paints, coats, and seals.

Polyol Esters have good high-temperature stability, hydrolytic stability and low-temperature properties, low volatility and low Viscosity Index; the polyol esters also may have more effect on paints and cause more swelling of elastomers. To take advantage of their miscibility with hydrofluorocarbon (HFC) refrigerants, polyol esters are used in refrigeration systems.

d.  Polyethers:

In this group, we can find Perfluorinated Polyethers (PFPE) with a density nearly twice that of hydrocarbons, they are immiscible with most of the other base oils and non-flammable under all practical condition. Very good viscosity-temperature and viscosity-pressure dependence, high oxidation and water stability, inert chemically and radiation stable; these properties joined their shearing stability. They are suitable as hydraulic fluids in spacecraft and as a dielectric in transformers and generators.

Polyphenyl Ethers have excellent high-temperature properties and resistance to oxidation but they have fair viscosity-temperature properties, they are used as hydraulic fluid for high temperature and radiation resistance.

Polysiloxanes or Silicones have high viscosity index, over 300, low pour point, high-temperature stability, and oxidation stability so run well in a wide range of temperatures; they are chemically inert, non-toxic, fire-resistant, and water repellent, they have low volatility and are compatible with seals and plastics. Their disadvantage is formation of abrasive silicon oxides if oxidation does occur, effective adherent lubricating films are not formed due to their low surface tension, and also show poor response to additives. They are used are brake fluids and as antifoam agents in lubricants.

The table compares different synthetic base oils properties against mineral oil.

Table 3 Comparison among base oils.

5.  Bio-bases Oils.

They are mainly produced from soybeans, rapeseed, palm tree, sunflowers, and safflowers. Their advantages are high biodegradability, superior lubricity, higher flash point, and viscosity index; but their pour point is high and the oxidative stability is poor, also the recycling is difficult.
The main applications are hydraulic fluids, transmission fluids, gear oils, compressor oils, and greases. Better when an application is total loss, indoors or where low pour point is not an issue, food industry or environmentally-sensitive areas.

1. Introduction to Tribology and Lubrication