Does Engine Oil Have a Shelf Life?

[AubreeMarie]

Engine oil does have a shelf life. Unopened engine oil typically lasts 3-5 years, while opened engine oil has a shelf life of about 6 months. The following are the functions of engine oil: 1. Cleaning: The cleaning process is achieved through the circulation of oil within the engine; 2. Sealing: Oil forms a film in the gaps between components, which acts as a seal to ensure the tightness of the cylinders; 3. Cooling: During engine operation, a large amount of heat is generated. Most of this heat is dissipated through the engine's cooling system, while some is absorbed by the oil from surfaces like the cylinders and pistons, then carried to the oil pan for dissipation; 4. Anti-rust: Engine oil contains multi-functional additives like rust inhibitors, which form a dense, well-arranged protective layer on metal surfaces, effectively preventing the intrusion of corrosive substances. 5. Cushioning: During engine startup, acceleration, or significant load changes, components such as piston pins, connecting rod ends, and crankshaft bearings experience intense vibrations. Oil with appropriate viscosity can absorb some of the impact energy, providing a cushioning effect.