Why is it necessary to change engine oil regularly?
1 Answers
Engine oil, much like blood circulating in the human body, flows between various moving components within the engine. It serves four primary functions: lubrication, cooling, cleaning, and sealing. Among these, lubrication is the most crucial role. It forms a protective oil film on the surfaces of interacting engine parts, which not only ensures smooth high-speed operation but also minimizes wear on contact surfaces. The formation of this oil film primarily relies on the oil's viscosity. However, after prolonged engine use, this viscosity degrades, compromising the oil film's effectiveness, necessitating regular oil changes. Additional details about engine oil are as follows: 1. Consequences of not changing oil: Failure to change oil may initially cause abnormal engine wear, increased noise, and higher fuel consumption. In severe cases, it can lead to seizure of critical components like the crankshaft or camshaft, rendering the engine inoperable. 2. Composition of engine oil: Typically consisting of base oils and various additives, engine oil is a chemical product derived from petroleum refining. Operating in complex environments with high temperatures (approximately 90°C for Japanese vehicles and 110°C for European/American models), it undergoes oxidation, generating impurities and causing gradual separation of resinous substances – all of which degrade oil performance. 3. Oil oxidation process: As pistons reciprocate in cylinders, high-temperature/pressure gas mixtures infiltrate the crankcase through piston-cylinder gaps, accelerating oil oxidation and causing darkening. 4. Factors affecting oil performance: During cold starts, gasoline injected into cylinders can seep into the crankcase, mixing with oil. This dilution reduces viscosity and impairs oil functionality. 5. Lubrication breakdown: Friction between engine components (e.g., pistons/cylinders, crankshaft/bearings) generates metal particles. While oil filters capture larger debris, microscopic particles remain in circulation, gradually diminishing lubricating properties over time.
