Why does the engine sound quieter after an oil change?

[Lila]

After changing the engine oil, the lubrication capability improves, resulting in reduced engine noise. Here are some key points about engine oil: 1. Composition: Engine oil consists of base oil and additives. The base oil is the primary component that determines the fundamental properties of the lubricant, while additives play a crucial supplementary role. 2. Oil types: The SAE viscosity classification for winter oils includes grades such as 0W, 5W, 10W, and 15W. The 'W' stands for winter, and a smaller number before the W indicates lower low-temperature viscosity and better performance in colder climates. The SAE viscosity classification for summer oils includes grades like 20, 30, 40, and 50, where higher numbers represent greater viscosity and better performance in higher temperatures.