About Base Oil

Base oils are used to produce products such as lubricating greases, motor oils, and metalworking fluids. Different products require different compounds and properties in oil. One of the most important factors is the viscosity of the liquid at different temperatures. Whether a crude oil is suitable for base oil conversion is determined by the concentration of base oil molecules and how easily they can be extracted.

Base oil is produced by refining crude oil. This means that the crude oil is heated so that the various spirits can be separated from each other. During the heating process, the light and heavy hydrocarbons are separated – the light type can be refined to produce gasoline and other fuels, while the heavier type is suitable for bitumen and base oils.

Characteristics of base oils used to determine their performance may include:

• Pour point

• Viscosity and viscosity index
• Purity
• swing
• Thermal stability
• Hydrolytic stability (resistance to water)
• oxidation

Sulfur and saturated content

When choosing a lubricant, it is important to know what base oil is used. Since base oil is 80-99% a lubricant, you need to know what base oil you are using.

The American Petroleum Institute (API) has classified base oils into five groups, characterized by saturation level, sulfur level and viscosity index.

Group I, II, and III are from crude oil (mineral oil), Group IV is a fully synthetic oil, and Group V is for all base oils that do not fall into one of the other groups.

Group I

Group I oils are solvent refined, which is a simpler refining process and makes them the least refined and therefore the cheapest base oils available. Solvent-refined oils are usually composed of a mixture of different hydrocarbon molecules that cannot be distinguished in the refining process.

Group II

Group II base oils undergo hydro-cracking, which is a more complex process than group I oils. Hydro-cracking is a process that breaks down large hydrocarbon molecules into smaller molecules. The price of group II oils is close to that of group I oils.

Group III

Group III oils go through an even longer process than Group II oils. This process, called severe hydro-cracking, is also more severe. More pressure and heat are applied during the refinery process. This results in a purer, higher quality base oil. Even though Group III oils are derived from crude oil, they are sometimes described as synthetic hydrocarbons.

Group IV

Group IV base oils are polyalpha olefins. These are not extracted but are made from small uniform molecules.

Group V

Group V oils consist of any type of base oil other than those listed in the previously defined groups.