Can engine oil opened for one year still be used?

[LolaMarie]

Engine oil that has been opened for one year cannot be used because it has been too long. Once the oil cap is opened, it should be used as soon as possible; otherwise, the oil will deteriorate, and its lubrication performance will decrease. The functions of engine oil are: 1. To separate the surfaces of relatively sliding parts, thereby reducing wear; 2. To bring heat back to the oil tank and then dissipate it into the air, helping the radiator cool the engine; 3. To circulate carbon deposits, sludge, and worn metal particles from engine parts back to the oil tank, flushing away dirt generated on the working surfaces of the parts through the flow of the lubricating oil. Signs that indicate the need to change the engine oil include: 1. Checking the viscosity of the oil—if there is no viscosity, the oil needs to be changed; 2. The color of the oil turns black; 3. Excessive black particles, metal shavings, or carbon deposits in the oil; 4. The smell of the oil is abnormal.