"Base Oil" in Farsi means "Base Oil" in English. Base oils are a type of oils that are used in the production of lubricating products such as motor oil and industrial oils. These oils are often obtained from refined crude oil and are widely used to produce products with the required lubricating properties in various industrial and automotive sectors. Base oils are typically classified by viscosity and degree of refinement. They can fall into several categories, including mineral, synthetic, and semi-synthetic base oils. Each of these types has its own characteristics that are suitable for different applications. Base oils are classified into different categories based on the level of refinement and physical and chemical properties. This category includes the following: 1. Group I base oils: These types of oils are refined in the traditional way and usually have a high amount of impurities such as sulfur, nitrogen and unsaturated substances. These oils are suitable for simpler applications. 2. Group II base oils: These oils are refined using more advanced processes and have fewer impurities than Group I. They have better properties such as oxidation stability and viscosity. 3. Group III base oils: These types of oils are highly refined and are commonly known as "fully synthetic oils". They have superior performance at high and low temperatures as well as high stability against oxidation. 4. Group IV base oils (PAO): These oils are fully synthetic and are made from polyalpha-olefins (PAO). They have properties such as high thermal stability and excellent performance at low temperatures. 5. Group V base oils: This group includes all other base oils such as esters, silicones and polyglycols. They are used in special applications that require special properties such as compatibility with additives or special environmental properties. Choosing the right base oil depends on the specific application needs, including operating temperature, application environment, pressure and other operating conditions. Also, issues related to the environment and degradability can also be influential in choosing the type of base oil.