Motor oil, or engine oil, whether fully or semi synthetic, is used to provide the necessary lubrication for the internal combustion engine. While it's main function is to lubricate moving parts, motor oil also cleans, inhibits corrosion, improves sealing, and cools the engine by carrying heat away from moving parts.
Motor oils are themselves derived from petroleum based and non petroleum synthesized chemical compounds. The motor oils today are mostly blended using base oils composed of hydrocarbons, polyalphaolefins (PAO), and polyinternal olefins (PIO).
The Society of Automotive Engineers (SAE) has established a numerical code system for grading motor oils according to their viscosity characteristics.
This SAE viscosity grading's runs from low to high viscosity: 0, 5, 10, 15, 20, 25, 30, 40, 50 or 60.
The numbers 0, 5, 10, 15 and 25 are also suffixed with the letter W, designating their "winter" or cold-start viscosity.
Thus the number 20 comes with or without a W, depending on whether it is being used to denote its cold or hot viscosity grade.
It is also worthy to note that the SAE has a separate viscosity rating system for gear, axle, and manual transmission oils. These should not be confused with engine oil viscosity, the higher numbers of a gear oil (e.g. 75W-140) do not mean that it has higher viscosity than an engine oil.
The temperature range motor oils are exposed to can be wide, ranging from the cold temperatures experienced in the winter before the vehicle is started, to the hot operating temperatures when the vehicle is fully warmed up in hot summer weather or climates.
Each oil will have a high viscosity when cold and a lower viscosity as it gets warmer, this being the engine's operating temperature. The difference in viscosities for most single-grade oil is too large, so to bring the difference in viscosities closer together to a level that can be achieved, special polymer additives called viscosity index improvers (also known as 'VIIs') are added to the oil.
Once added, the additives turn the oil into a 'multi-grade motor oil'. The idea is to produce an oil that will have the viscosity of the base grade when cold and the viscosity of the second grade when hot.
This enables one type of oil to be used all year rather than having to use one in the winter and another in the summer.
exol have a reputation for the highest quality products, flexible service, and fast delivery our outstanding technical support teams are there to help you choose the right oils / lubricants / cleaners and greases for every application.
Our research and development team have also developed motor oils designed to extend oil life as far as is possible.
Whatever your needs, our specialist team are there to assist, and if the right type of product is not available now, we can develop one (subject to quantities of course).