Does engine oil have an expiration date?
2 Answers
Engine oil does have an expiration date. Generally, the shelf life of engine oil (fully synthetic, semi-synthetic, mineral oil) is 4-5 years. Below is more information about engine oil: 1. Mineral oil: Mineral oil is the residual oil left after refining gasoline and heavy oil from petroleum. Although it is a natural oil, it contains more impurities. It is cheaper compared to semi-synthetic and fully synthetic oils but offers poorer lubrication for the engine and has a shorter service life. 2. Semi-synthetic oil: Semi-synthetic oil is a middle ground between mineral oil and fully synthetic oil. It contains a large amount of anti-corrosion additives to improve the oil's stability and high oxidation resistance. 3. Fully synthetic oil: Among the three types, fully synthetic oil is of the highest quality and durability, and it is also the most expensive. Typically, it can last for 10,000-12,000 kilometers in a car without deteriorating. 4. Hazards of water contamination in engine oil: If a small amount of water enters the engine and mixes with the oil, the oil quality deteriorates. Oil containing water can increase wear on engine components, potentially leading to increased engine noise and vibration during future vehicle operation.
As a car enthusiast, I often change my own engine oil, and this is a good question. Indeed, engine oil has a shelf life. Unopened, it can typically last 3 to 5 years, but once opened and exposed to air, it begins to oxidize and degrade. It's best to use it within six months to a year. Last time, I bought a large drum, forgot about it, and after a year, I noticed it had changed color. Testing it, I felt the viscosity was insufficient and lubrication was much worse—it almost damaged my engine pistons. The reason is that the additives in the oil degrade, and absorbing moisture or dust affects its anti-corrosion properties. For stored, unused oil, remember to keep it in a cool, dry place—don’t leave it in a garage corner where heat can thin it out. Before each maintenance, check the date on the oil container label for safety. Saving money by using expired oil may lead to premature major repairs, which really isn’t worth it. I make it a habit to buy fresh oil periodically to avoid any mishaps.
