Can 5-year-old engine oil be used?

[OGage]

Unopened engine oil can be stored for 5 years, but opened engine oil can only be stored for 12 months. It is not recommended to use expired engine oil. The national standard for engine oil shelf life is 5 years, with some types lasting up to 12 years. Generally, engine oil within 3 years should be fine. Engine oil is not a food or pharmaceutical product, so the General Administration of Quality Supervision does not require products with a shelf life exceeding certain years to indicate an expiration date, which is why engine oil does not have a marked shelf life. Additionally, fully synthetic oil has a longer shelf life than mineral oil. To maintain the performance of lubricating oil, it is generally recommended to store it in a cool, dry place to prevent contamination by water or other impurities.

[AlexAnn]

I think it's best not to use engine oil that has been stored for 5 years, as oil deteriorates over time and its lubricating effectiveness diminishes significantly. When I was younger, I also stored engine oil, but later discovered that after more than three years, it may oxidize or absorb impurities. Using such oil can accelerate engine wear, and even lead to oil seal leaks or oil burning issues. If the storage environment is poor, such as in a hot garage or damp place, the oil deteriorates even faster. Rather than saving a little money this way, it's more reliable to change to fresh oil regularly and check its condition every 5,000 kilometers or every six months. Remember to choose reputable brands; for example, full synthetic oils have a slightly longer shelf life, but don't delay too long—safe driving is more important.

[BarrettFitz]

I'm a practical person, so when it comes to 5-year-old engine oil, I sincerely advise against using it. Once engine oil expires, the oil film tends to break easily, failing to protect the engine. Instead, it may clog the oil passages or cause overheating. The repair costs could end up being much higher than the price of new oil. I cherish my car dearly, and whenever I see friends using old oil, I always remind them—just imagine the scenario of engine knocking or increased fuel consumption. If stored properly, it might still be usable within three years, but five years is too risky. By the way, always check the production date label when buying oil, and don't stockpile too much. Buying as you need it is the most cost-effective and hassle-free approach.

[DiAlessandra]

If the engine oil has been sitting for five years, I recommend replacing it without hesitation. Deteriorated oil accumulates moisture and dust, losing its lubricating power. Driving with it can cause the engine temperature to rise, leading to cylinder scoring, and repairs can cost thousands—not worth the risk. Among the car owners I know, some have suffered major losses using old oil, with their vehicles breaking down mid-journey, causing both inconvenience and expense. While storing oil should avoid direct sunlight and prolonged exposure to air, five years is beyond the limit—safety first.