Engine Oil Characteristics And Requirements

Main features
The engine is the heart of the car. There are many metal surfaces in the engine that rub against each other. These parts move fast and in a poor environment. The operating temperature can reach 400℃ to 600℃. The new technology can make natural gas into a crystal-pure fully synthetic base oil. On this basis, a unique power cleaning technology is added to create a lubricant with super clean and protective performance. Under such harsh working conditions, only qualified lubricants can reduce the wear of engine parts and extend the service life. The motor oil on the market can be simply divided into mineral oil and synthetic oil due to its different base oils (vegetable oil is not counted due to its scarce production). Synthetic oil is further divided into: fully synthetic and semi-synthetic. Lubricant base oils are mainly divided into two categories: mineral base oils and synthetic base oils. Mineral base oils are widely used and used in large quantities (about 95% or more), but some applications must use products formulated with synthetic base oils.
Requirements
As a machine, the engine has some common requirements for lubricants compared to general machines, such as the requirement for appropriate viscosity, certain anti-oxidation, anti-wear, anti-corrosion and viscosity-temperature performance requirements. But the engine is a special kind of machinery, and its requirements for lubricating oil have their own special aspects. Its special features are mainly:
1) The general requirements for the engine are small size, light weight, compact structure, and high output power, so the load on its unit friction surface is very large.
2) In addition to friction heat, it is also affected by combustion heat, so the temperature of the friction surface is very high, which reduces the viscosity of the lubricating oil and makes it difficult to form an oil film.
3) The high-temperature and high-pressure combustion gas in the combustion chamber will leak into the crankcase through the gap between the piston, piston ring and cylinder liner. These combustion gases are gases and certain particulate matter (soot) produced by the complete combustion and incomplete combustion of fuel and a small amount of lubricating oil, which usually become the main components of crankcase blowby, which will contaminate the lubricating oil and promote its oxidation under certain conditions.
4) The lubricating oil needed around the combustion chamber enters through the gap between the piston and the cylinder liner, and the gap between the valve stem and the valve guide, so it is more difficult to supply oil.
5) The piston and valve parts reciprocate during operation, so the relative speed is zero at the upper and lower dead points, making it difficult to form an oil film. The piston pin and bushing are in swinging motion, and it is difficult to form an oil film.
6) The temperature difference between the engine when it is stopped and when it is running for a long time is very large. Due to the thermal expansion and thermal deformation of the parts, it is difficult to control the constant gap of some friction pairs. Adhesion sintering may occur due to too small gaps, or damage may occur due to impact and vibration caused by too large gaps. In these cases, it is difficult for the oil film to adhere.
7) There are many friction pairs in the engine, such as pistons and cylinder sleeves, crankshaft journals and bearings, cams and followers, gears, etc. Although they have different requirements for the lubricating performance of lubricants, only one lubricant can be used in an engine (except for large marine diesel engines). Therefore, when selecting lubricants, multiple lubrication conditions must be taken into account.
8) The operating environment of automotive engines is complex, such as large changes in temperature, humidity, atmospheric pressure, dust, etc. At the same time, because the engine oil often contains elements such as sulfur and lead, it will promote corrosion and wear of certain parts.