What color indicates that engine oil needs to be changed?

[StAmara]

Engine oil needs to be changed when it turns brown or black. Fresh engine oil is light yellow and transparent. After being added to the engine, it turns brown due to the accumulation of carbon deposits from prolonged engine use. With further usage, it eventually turns black. Engine oil is often referred to as the lifeblood of the engine, serving not only as a lubricant but also providing cleaning, sealing, buffering, rust prevention, and heat dissipation functions. Without engine oil, the engine cannot operate properly. During normal operation, the oil forms a protective film on the surfaces of engine components, preventing direct contact and friction between parts.