Base oil

BASE OIL
Base oils are used to manufacture products including lubricating greases, motor oil and metal processing fluids. Different products require different compositions and properties in the oil. One of the most important factors is the liquid’s viscosity at various temperatures. Whether or not a crude oil is suitable to be made into a base oil is determined by the concentration of base oil molecules as well as how easily these can be extracted.
Base oil is produced by means of refining crude oil. This means that crude oil is heated in order that various distillates can be separated from one another. During the heating process, light and heavy hydrocarbons are separated – the light ones can be refined to make petrol and other fuels, while the heavier ones are suitable for bitumen and base oils
Group I
Originating in the 1930s, the least refined type which is produced by Solvent Refining. It usually consists of conventional petroleum base oils. An improvement to the refining process in the 1960s called hydro-treating made this base oil more stable, less reactive, and longer lasting than the earlier base oils.
API ( American Petroleum Institute ) defines group I as “base stocks contain less than 90 percent saturates and/or greater than 0.03 percent sulfur and have a viscosity index greater than or equal to 80 and less than 120”.
Group II
Originating in 1971, a better grade of petroleum base oil, which may be partially produced by Hydrocracking. All impurities will be removed from the oil leading to clearer color.
API defines group II as “base stocks contain greater than or equal to 90 percent saturates and less than or equal to 0.03 percent sulfur and have a viscosity index greater than or equal to 80 and less than 120”.
Group III
Originating in 1993, the best grade of petroleum base oil, since they are fully produced by Hydrocracking, Hydroisomerization, and Hydrotreating, which make these oils purer.
API defines group III as “base stocks contain greater than or equal to 90 percent saturates and less than or equal to 0.03 percent sulfur and have a viscosity index greater than or equal to 120”.
This group may be described as Synthetic Technology oils or Hydro-Cracked Synthetic oil. However, some oil companies may call their products under this group as synthetic oil.
Group IV
Originating in 1974, consists of synthetic oils made of Poly-alpha-olefins (PAO). Group IV base oils have a viscosity index range of 125 – 200.
Poly-alpha-olefins (PAO) oils have a higher oxidative stability in extreme temperatures, and also have exceptionally low pour points, which makes them much more suitable for use in very cold weather (as found in northern Europe), as well as in very hot weather (as in Middle East).
Group V
Originating in the 1940s, any type of base oil other than mentioned in the previously defined groups.
They include, among others, naphthenic oil and polyesters