Can engine oil still be used after more than 5 years?
2 Answers
Engine oil that has been stored for more than 5 years should not be used. Unopened engine oil typically has a shelf life of about 5 years. If the oil has been stored for too long or improperly, its chemical components will inevitably deteriorate. It is advised not to use such oil to avoid damaging the valve seals and the engine. Precautions for using engine oil: Storage conditions: Under proper storage conditions, engine oil can last for 4 to 5 years. Once opened, if sealed properly, it can generally be stored for about a year. The main factor affecting the shelf life of engine oil is the storage conditions. The greater the temperature fluctuations and humidity in the storage environment, the faster the oil will deteriorate. For every 10°C increase in temperature, the oil's lifespan is halved: Never leave the oil cap off and expose the oil to sunlight. The correct practice is to store the oil in a sealed, cool place. Poor sealing can lead to oxidation when the oil comes into contact with air, and high temperatures accelerate this oxidation. Additionally, large temperature fluctuations can easily cause condensation, and moisture can lead to lubricant deterioration. If the oil has been stored for more than 3 months, it should be replaced before the next use: If the oil in the car has been used for a relatively long period, such as covering half the usual maintenance interval mileage, the storage time should be reduced. It is recommended to replace the oil if it has been stored for more than 3 months before the next use. Leftover oil from maintenance, if stored properly, can last for about a year. However, for safety reasons, it is advisable to use it within six months.
When I was younger, I stored a bottle of motor oil and kept it for almost seven years. Thinking it was still usable, I added it to my car. However, within just a few days of driving, the engine became extremely noisy. Upon inspection, it turned out the oil had completely deteriorated. Generally, motor oil past five years should be avoided—it gradually oxidizes, absorbs moisture, and its additives like lubricants lose effectiveness. Insufficient lubrication increases friction between engine components, leading to louder noise and accelerated wear in mild cases, or potentially damaging piston rings or oil pumps in severe cases, with repair costs that can be shockingly high. I learned my lesson and now regularly check the oil’s date. The oil change cycle is typically every six months to a year, and it must be stored in a cool, dry place. Expired motor oil is like expired food—it’s best to discard it immediately. Safety comes first.
