Classification of lubricating oil
Lubricants are divided into industrial lubricants and automobile lubricants. Among them, vehicle lubricating oil includes engine oil, water tank and cooling system oil, automatic transmission oil, gear oil (for manual transmission), brake and clutch system oil, grease, etc.
Composition of lubricating oil and concepts of synthetic oil and mineral oil.
Lubricating oil consists of base oil and additives. For engine oil, base oil usually accounts for about 90%, and the rest is additives. The quality of base oil is very important to the performance of lubricating oil, which provides the most basic lubrication, cooling, oxidation resistance and corrosion resistance of lubricating oil. However, in order to improve the performance of lubricating oil, lubricating oil also contains additives to improve its comprehensive performance. The additives of engine oil mainly include: anti-oxidation additives, anti-rust additives, anti-corrosion additives, anti-foaming additives, viscosity index improvers, pour point depressants, cleaning additives, dispersants, anti-wear additives and so on. The above additives are not enough, and many properties need to be balanced comprehensively. Therefore, it is necessary to carry out bench test of lubricating oil to determine or evaluate the performance of the formula through its comprehensive performance in the engine.
Because the content accounts for the vast majority, the performance of base oil is very important to the performance of finished lubricating oil. Traditionally, the base oil extracted from petroleum by physical distillation is called mineral oil (some non-deeply hydrogenated base oils are also called mineral oil), and synthetic oil, as its name implies, is the base oil obtained by chemical synthesis (most of its components do not exist directly in petroleum). There is no exact definition of synthetic oil and mineral oil, which is commonly known as saying. API (api gravity) classifies base oils into five categories, and the third and fourth types of base oils are usually called synthetic oils.
Common synthetic oils are: PAO, XHVI and esters. In addition, the performance of VHVI base oil is between synthetic oil and mineral oil. Although some people call it synthetic oil, its properties (such as viscosity-temperature characteristics, oxidation resistance, etc.) are far from those of PAO, XHVI and esters. PAO and XHVI are the most widely used engine oil base oils, of which XHVI is a synthetic base oil with patented technology of Shell, synthetic engine oil of Mobil mainly uses PAO as raw material, and the synthetic oil of Castrol mostly uses esters as base oil. The performance of XHVI and PAO is similar, but the antioxidant performance of ester engine lubricating oil is different from the former two.
At present, China's industry keeps up with western new technologies and uses many products from the United States, Japan and Europe. Therefore, the standards of these countries (such as American SAE, Japanese JIS, European CCMC, German DIN, etc. ) has been gradually cited, and the current lubricating oil standards in China (SY, SH, GB) are gradually approaching these standards, especially referring to American SAE standards. Global economic integration is an inevitable trend, and the standards adopted by lubricating oil industries in various countries are gradually consistent or equivalent to each other, and China is no exception. 1. Classification is consistent with ISO (National Organization for Standardization): * * * Thirteen categories. The main categories of internal combustion engine oil, gear oil, hydraulic oil and other oil products are classified according to the latest national standards, and the Chinese standards are synchronized with the national standards.
However, in practical application, there is an obvious gap between China's lubricants and developed countries. For the internal combustion engine oil with the largest consumption, we generally use SD and se grades, while developed countries have used SG and SH grades, with a difference of 2 or 3 grades (in alphabetical order). China can now produce SE, SF and even SH grade internal combustion engine oils, but the key raw materials: composite additives for internal combustion engines still basically rely on imports; This is the actual gap between China and the international advanced level.