ACEA is the European Association of Car Manufacturers. It sets the most modern quality levels for automobile lubricants, essentially aimed at European vehicles. These quality levels replace the earlier CCMC. A1, A3 and A5 for petrol cars; B1, B3 and B5 for diesel cars; E4, E6, e7 and E9 for heavy diesel vehicles.

This term is applicable to those engine lubricants of broad application, which ensure suitable lubrication both in petrol and diesel cars.

Made with lubricant bases obtained directly from distillation of petroleum.

Made with mixtures of mineral and synthetic bases.

Made with bases which come from complex transformations or synthesis.

Compounds added to the base oils in small amounts to give a finished lubricant of the desired characteristics and performance.

An oil's ability to eliminate air trapped inside it. Aeroemulsion is very important in turbine oils and increasingly in high severity hydraulic oils. It is an intrinsic property of the base oil and cannot be corrected with additives.

An additive able to reduce friction between moving parts.

An additive which prevents water vapour from combustion or from condensation from the atmospherre creating rust on the engine parts.

An additive which makes the oil take longer to become degraded by reducing its oxidation.

The API is the American Petroleum Institute. It sets quality levels for automobile lubricants, essentially aimed at American manufacturers. Its quality levels are identified with two letters. Those beginning with S refer to petrol vehicles and those with C to diesel engines. The second letter, after the S or C, indicates the quality level, in rising order, e.g., API SM is the highest quality level for petrol cars and CI-4 and CJ-4 are the highest quality level for diesel engines.

A lubricant fluid obtained from petroleum distillation or complex transformations. It is the raw material from which lubricants are made.

Cars which often have multivalve and turbo systems, with a cylinder capacity of 1.8-2.2 litres and a horse power of 90-150, e.g., Audi 80, BMW Series 3, Citröen Xantia, Ford Mondeo, Nissan Primera, Opel Calibra, Peugeot 406, Renault Laguna, Seat Toledo, Volkswagen Passat...

Since 1995, nearly all the designs of all motorcycle and scooter manufacturers have included an independent circuit for oil, with its own pump and tank. Depending on the manufacturer, the tank size varies from 1 to 1.3 litres. The oil is sucked from a tank by a pump which sends it directly to the air/petrol intake after the carburettor.

This not an essential property of the lubricant, nor does it say anything about its quality. It is measured according to a scale described in the standard ASTM-D-1500, which assigns low numbers to light-coloured oils and high numbers to dark ones. The colours of base oils may be changed by additives, so that the colour of the finished oil will be determined by these two variables.

Cars with a cylinder capacity of 1.4 to 1.9 litres and a horse power of 75-110, e.g., Citröen ZX, Fiat Tempra, Nissan Sunny, Peugeot 306, Renault Megane, Ford Escort, Opel Astra,Volkswagen Golf, Seat Cordoba...

The weight of a substance per unit of volume. It should not be confused with VISCOSITY. For example, water is denser than oil (it weighs more) but is more fluid (less viscous). It is measured according to standard ASTM-D-4052

An additive which prevents solidification or lack of fluidity of the lubricant at very low temperatures.

This is a measure of the capacity of an oil to separate from an equal volume of water when they have been mixed together.

Detergence is the characteristic or quality of an oil which prevents the engine from becoming dirty and acid products forming which corrode and wear its parts. In an engine, it could be defined as the lubricant's ability to remove combustion residues and impurities from metal surfaces.

An additive which prevents carbon residues from combustion and lacquers and varnishes from degradation of the oil becoming set on metal surfaces.

This is the quality which allows an oil to prevent accumulation of insoluble residues produced by combustion, keeping them in fine dispersion throughout the circuit.

An additive which prevents particles from sticking together, forming precipitaiton and sludge within the lubricant.

A measure of an oil's tendency to form foam. This test, included in standard ASTM-D-892, tells how an oil would behave if it were stirred or air were introduced in it.

A property which prevents two surfaces under a heavy work load from becoming "welded" together. This property is very important for industrial and automobile gears.

High-performance cars, generally with more than 4 cylinders, multivalve systems, a cylinder capacity of more than 2.5 litres and a horse power greater than 150 hp, e.g., Audi 100, BMW Series 5, Opel Omega, Peugeot 605, Reanult Safrane, Volvo Series 800, Mercedes Class E...

Top-of-the-range sports cars with petrol engines. They are high-speed cars with high specific power (all having multipoint injection technology and increasingly turboinjection).

This is a measure of the change in viscosity with temperature. ASTM-D-2270 is the standard describing it. Typical values for the viscosity index are 95 (for normal or "single grade" oils) and between 125 and 150 (for "multigrade" oils). Thge higher the number, the less the viscosity changes with temperature.

As well as the SAE scale of viscosity, basically used for automotive oils (engine, gear boxes, transmissions, etc.), there is another viscosity scale used for industrial lubricants (hydraulics, turbines, compressors, pneumatic tools, industrial gears, heat transmission, dielectrics, etc.). This is the I.S.O. (International Standard Organization) scale of viscositiy, described in standards DIN 51519 and ISO 3448. This scale measures viscosity in centistokes at 40ºC and dfines margins of tolerance within each ISO grade.

In engines, the lubricant keeps the engine clean by attracting all the residues produced by combustion.

The science of the procedures to reduce friction between two surfaces in movement relative to each other, its context and consequences.

Any solid, semi-solid or liquid substance, whatever its origin, which serves to reduce friction between moving parts and mechanisms.

To reduce friction and rubbing between metal parts in contact by placing a lubricant film between them.

An additive with the capacity to keep the oil fluid at low temperatires and sufficiently viscous at the engine's working temperatures, i.e., it keeps the oil fluid at the different temperatures.

Lubricants made with bases obtained directly from petroleum distillation .

Oils which need to be changed according to the season of the year because their viscosity changes with temperature.

Oils with a minimum viscosity change with temperature. These oils respond to the requirements of use at both high and low temperatures and can be used all year round. An SAE MULTIGRADE oil is one complying with two SAE scales at the same time (e.g., 80W90; 15W40; 10W30, etc.).

One of the great innovations in motor engineering has been the development of multivalve engines. Engine performance is considerably improved, as it is able to "breathe" better and more. There are cars with 4 valves per cylinder (2 intake and 2 exhaust valves per piston):

* 16 valves (4-cylinder engine) (e.g., Peugeot 406 2.0 16V ST, Renault Laguna 2.0 S RXE, Ford Mondeo Ghia 2.0 16V, Citröen Xantia 2.0 16V SX, Volkswagen Golf Gti.)
* 24 valves (6-cylinder engine) (e.g., Alfa Romeo 164 3.0 Super V6 24V, Citröen XM V6 24V Exclusive...) 5 valves per cylinder (3 intake and 2 exhaust valves per piston)
* 20 valves (4-cylinder engine) (e.g., Volkswagen Passat 90 CV i, Audi A4 1.8.)
* 30 valves (6-cylinder engine) (e.g., Volkswagen Corrado V6 2.8l 193CV, Audi A8 4.0l...).

The highly complicated structure of these multivalve systems requires a high-performance lubricant guaranteeing perfect balance between fluidity and control of wear.

Oil and petrol are mixed at the start, using the petrol tank for this. This system is typical of traditional scooters, motorcycles and mopeds (made before 1995) and other 2-stroke engines, such as:

* Water extraction pumps
* Electricity generators
* Garden machinery (lawn mowers, burring machines, hedge cutters, etc.)
* Power saws
* Garden tractors
* Etc.

The lubricant protects the engine parts from the corrosive effects of agents produced by combustion and other substances.

This is reached just after the ignition point, when a temperature is reached at which the oil continues to burn for at least 5 seconds. It is described in standard ASTM-D-92.

This is the minimum temperature at which a given oil maintains itself fluid. Logically, it is desirable for the freezing point of an engine oil to be as low as possible. It is described in standard ASTM-D-97.

Indicates the temperature to which an oil can be heated without risk of igniting (flashing) in the presence of a naked flame. It is described in standard ASTM-D-92, when it is measured in an open vessel.

In engines, the lubricant cools bearings, cylinder walls and the interior of pistons (places where the engine's traditional refrigeration system does not reach).

All the forces which oppose the relative movement of two surfaces in contact with each other.

This refers to a scale of viscosity used throughout the world, established by the American Society of Automotive Engineers, for all oils used in automobiles. This classification gives the SAE engine oil grades 0W, 5W, 10W, 15W, 20W, 25W, 20, 30, 40, 50 and 60, while for manual gear boxes, differentials transmissions it assigns SAE 70W, 75W, 80W, 85W, 90, 140, 250. Viscosity levels in SAE grades are measured at 100º C. If followed by the letter W, it shows that it was measured below 0º C. For example, SAE 20W-50: the 20W shows the viscosity at low temperatures and 50 the viscosity at high temperatures.

Since 1995, nearly all the designs of all motorcycle and scooter manufacturers have included an independent circuit for oil, with its own pump and tank. Depending on the manufacturer, the tank size varies from 1 to 1.3 litres. The oil is sucked from a tank by a pump which sends it directly to the air/petrol intake after the carburettor.

In engines, the lubricant contributes towards sealing of the combustion chamber, preventing gases leaking into the engine casing when adequate compression is maintained.

Lubricants made with mixtures of mineral and synthetic bases.

Those made with bases produced by complex transformations or synthesis.

Since 1995, nearly all the designs of all motorcycle and scooter manufacturers have included an independent circuit for oil, with its own pump and tank. Depending on the manufacturer, the tank size varies from 1 to 1.3 litres. The oil is sucked from a tank by a pump which sends it directly to the air/petrol intake after the carburettor.

Oil and petrol are mixed at the start, using the petrol tank for this. This system is typical of traditional scooters, motorcycles and mopeds (made before 1995) and other 2-stroke engines, such as:

* Water extraction pumps
* Electricity generators
* Garden machinery (lawn mowers, burring machines, hedge cutters, etc.)
* Power saws
* Garden tractors
* Etc.

Super Tractor Oil Universal. This term is used by farm machinery manufacturers and users, applied to the multifunctional lubricants developed to lubricate the different systems in farm marchiner: diesel engine (atmosphere or turbo-injected), final drives, transmissions, hydraulic systems, oil-immersed brakes.

Total Basic Number. It is expressed in mg KOH/g of sample, and shows the power to neutralize acids from combustion.

These are modern, top-of the-range diesel cars with direct turboinjection. They provide lively acceleration and high top speeds, reaching 200 km/h. The provide performance (cylinder capacity and power) very similar to their petrol-engined counterparts.

Cars with a cylinder capacity of 1.4 - 1.9 litres and a horse power of 75-110, e.g., Citröen ZX, Fiat Tempra, Nissan Sunny, Peugeot 306, Renault Megane, Ford Escort, Opel Astra,Volkswagen Golf, Seat Cordoba...

Small cars with a cylinder capacity of up to 1.4 litres and horse power up to 75, e.g., Citröen AX, Fiat Punto, Nissan Micra, Peugeot 205, Renault Twingo, Seat Ibiza, Volkswagen Polo, Ford Fiesta, Opel Corsa, Peugeot 106,...

Pequeños utilitarios con cilindrada hasta 1.4 litros y potencia hasta 75 CV. Ejemplos: Citröen AX, Fiat Punto, Nissan Micra, Peugeot 205, Renault Twingo, Seat Ibiza, Volkswagen Polo, Ford Fiesta, Opel Corsa, Peugeot 106,...

Universal Transmission Tractor Oil. Concepto que se maneja entre los constructores y usuarios de maquinaria agrícola, que se aplica para aquellos lubricantes formulados para la lubricación en la maquinaria agrícola de: transmisiones, sistemas hidráulicos y frenos sumergidos en baño de aceite.

The most important property of a lubricant. It can be defined as a measurement of the resistance to flow of the oil. Viscosity varies with temperature, but this variation is not the same for all oils. When temperature rises, viscosity descreases. The less an oil's viscosity varies with temperature, the better its behaviour will be. Viscosity is measured according to the standard ASTM-D-445 and expressed in centistokes at 40 ºC or 100 ºC.