Why is the engine oil black when drained?

1 Answers
Rogers
07/29/25 1:05pm
Engine oil turns black when drained due to the following reasons: During prolonged vehicle operation, carbon deposits and sludge form inside the engine for various reasons. These contaminants are carried out by the oil as it cleans the engine, combined with high-temperature oxidation and oil degradation, resulting in blackened used oil. However, seeing black oil doesn't necessarily mean frequent oil changes are required. Engine oil, also known as engine lubricant, serves multiple functions including lubrication and wear reduction, auxiliary cooling, sealing and leak prevention, rust and corrosion protection, as well as shock absorption. Engine oil consists of base oil and additives. The base oil is the primary component of lubricants, determining their fundamental properties, while additives compensate for and improve deficiencies in base oil performance, providing certain new characteristics, making them essential components of lubricants.
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