Lubricating oil is a liquid or semi-solid lubricant used in various types of automobiles and machinery to reduce friction and protect machinery and processed parts. It mainly functions as lubrication, auxiliary cooling, rust prevention, cleaning, sealing and buffering (Roab).

As long as it is applied between two relatively moving objects, it can reduce the friction and wear of the two objects due to contact, which is the lubricating oil.

Lubricating oils generally consist of two parts, a base oil and an additive. Base oil is the main component of lubricating oil, which determines the basic properties of lubricating oil. Additives can make up for and improve the performance of base oil, and give some new properties. It is an important part of lubricating oil.

Lubricating base oils are mainly classified into mineral base oils, synthetic base oils and biological base oils. Mineral base oils are widely used and used in large quantities (more than 95%), but in some applications they must be blended with synthetic base oils and bio-oil base oils, thus allowing these two base oils to develop rapidly.

Mineral oil base oil is refined from crude oil. The main production processes of lubricating base oils include: atmospheric and vacuum distillation, solvent deasphalting, solvent refining, solvent dewaxing, white clay or hydrogenation supplementation. In 1995, China revised the current lubricant base oil standard, mainly revised the classification method, and added two types of special base oil standards for low-condensation and deep-refining. For the production of mineral-based lubricants, the most important thing is to choose the best crude oil.

The chemical composition of mineral base oils includes high boiling, high molecular weight hydrocarbons and non-hydrocarbon mixtures. Its composition is generally alkanes (straight chain, branched chain, multi-branched chain), cycloalkanes (monocyclic, bicyclic, polycyclic), aromatic hydrocarbons (monocyclic aromatic hydrocarbons, polycyclic aromatic hydrocarbons), cycloalkyl aromatic hydrocarbons, and oxygen and nitrogen , sulfur-containing organic compounds and non-hydrocarbon compounds such as gums and asphaltenes. Bio-based oils (vegetable oils) are becoming more and more popular, and they can biodegrade and rapidly reduce environmental pollution. Synthetic lubricating oil has excellent low temperature performance, good lubricating performance and long service life, and can be applied to environments such as high load, high speed, high vacuum, high energy radiation and strong oxidizing medium. Since all industrial companies in the world are looking to reduce environmental pollution, this "natural" lubricant has this feature. Although the cost of vegetable oil is high, the added cost is enough to offset the use of other mineral oils, synthetic lubrication. Environmental treatment costs brought by oil. According to the nature of crude oil and processing technology classification, it is divided into paraffin base oil, intermediate base oil, naphthenic base oil.