The performance of Class I base oil will be limited. Class II base oil has less impurities (aromatic hydrocarbon content is less than 10%), high saturated hydrocarbon content, good thermal stability and oxidation resistance, and its low temperature and soot dispersion performance are better than those of Class I base oil.
Class III base oil is far superior to Class I base oil and Class II base oil in performance, especially high viscosity index and low volatility. Some class III oils have the same performance as polyalphaolefin (PAO), but their prices are much cheaper than synthetic oils.
Compared with mineral oil, Class IV base oil contains no sulfur, phosphorus and metals, and because it contains no wax, its pour point is extremely low, usually below -40℃, and its viscosity index generally exceeds 140. However, the lubricity of PAO boundary is poor. Class V base oils are mainly other synthetic base oils.
The difference is mainly reflected in the different production processes:
The production process of 1 and Class I base oils is basically based on physical processes, and the hydrocarbon structure is not changed. The quality of base oils produced depends on the content and properties of ideal components in raw materials.
2. Class II base oil is prepared by combined process (solvent method and hydrogenation method). The process is mainly a chemical process, which is not limited by raw materials and can change the original hydrocarbon structure.
3. Class 3.III base oil is prepared by full hydrogenation process. Compared with Class II base oil, it belongs to hydrogenated base oil with high viscosity index, also called unconventional base oil (UCBO). ?
4. Class 4.IV base oil refers to poly-α-olefin (PAO) synthetic oil. Commonly used production methods include paraffin decomposition and ethylene polymerization. PAO can be divided into low polymerization degree, medium polymerization degree and high polymerization degree according to different polymerization degrees, which are used to prepare different oil products respectively.
In addition, due to its low polarity, its ability to dissolve polar additives is poor, and it has certain shrinkage to rubber seals, but adding a certain amount of esters can overcome these problems.
5. Synthetic hydrocarbons, esters, silicone oils, vegetable oils and regenerated base oils are collectively referred to as Class V base oils.
Extended data:
Ester oil characteristics:
Under normal circumstances, oil will form a continuous oil film between two contact surfaces. This oil film plays the role of liquid lubrication-preventing direct contact between metals, thus reducing friction.
Whether lubricating oil can provide liquid lubrication depends on whether a complete oil film can be formed on two metal surfaces. When this oil film breaks under heavy load, it will produce resistance and friction.
It can still maintain excellent lubricity when other base oils fail, which is the advantage of ester oils in critical lubrication.
References:
Lubricating base oil _ Baidu Encyclopedia