Does motor oil have an expiration date?

[SarahRose]

Motor oil does have an expiration date, typically lasting 4 to 5 years. The contamination and deterioration of stored motor oil are primarily caused by its exposure to moisture, oxygen, and impurities in the air. Therefore, opened motor oil must be sealed for storage. Under normal circumstances, the water content in motor oil is below 0.03%. When the water content exceeds 0.1%, the additives in the oil (such as antioxidants and detergents) will become ineffective, accelerating the oxidation process of the oil. Motor oil, also known as engine lubricant, serves to lubricate and reduce friction, assist in cooling, seal against leaks, prevent rust and corrosion, and provide shock absorption. The hazards of overfilling motor oil include: 1. Reduced engine power output; 2. Blue smoke from the engine exhaust pipe; 3. Sticking piston rings and clogged fuel injectors; 4. Crankshaft explosion; 5. Oil leakage.