Can engine oil older than 5 years be used?
2 Answers
Engine oil older than 5 years cannot be used because the shelf life of engine oil is 5 years. Oil that has exceeded this period is often in a deteriorated state and is not suitable for use. Engine oils on the market are divided into three types: mineral oil, semi-synthetic oil, and fully synthetic oil. The replacement cycle for ordinary mineral oil is six months or 5,000 kilometers; for semi-synthetic oil, it is about eight months or 7,500 kilometers; while fully synthetic oil has a replacement cycle of one year or 10,000 kilometers. Under normal circumstances, the consumption of engine oil is minimal. The primary reason for changing the oil is that the esters and polyolefins in the oil oxidize, and particles from engine component wear also enter the oil, reducing the oil's lifespan and causing its internal components to deteriorate. To ensure the performance of the engine oil, it is generally recommended to store it in a cool, dry place to prevent water and other impurities from entering. If the storage time of the engine oil exceeds four or five years or even longer, when opening the container for use, pay attention to whether there is any abnormal odor, sedimentation, or if the color appears cloudy or whitish. If any abnormal signs are present, it is best not to use the oil.
I've been in the auto repair industry for over a decade and have seen too many cars with engine problems caused by using old motor oil. Motor oil isn't like wine—it doesn't get better with age. After five years, its internal additives begin to break down, the oil oxidizes and thickens, and its lubricating ability drops significantly. For example, impurities can separate from the oil layer, increasing friction when added, accelerating part wear, and over time, the engine may start burning oil or even fail completely. When maintaining my own car, I never dare to take risks with old stock, even if the bottle is unopened, because temperature fluctuations can speed up aging. Fresh oil makes the car run smoothly and improves fuel efficiency, avoiding repair nightmares. Do the math: engine repairs can cost thousands, while an oil change is just a few hundred. I recommend regularly checking the oil's date and changing it every six months or 5,000 kilometers as suggested in the manual—don't risk big problems to save small money.
