Can Expired Engine Oil for Small Cars Still Be Used?
2 Answers
Expired engine oil for small cars cannot be used. Reasons why it cannot be used: Engine oil is a highly water-absorbent substance. Over time, it absorbs moisture from the air, leading to oil degradation. The chemical composition of expired oil may have already changed, and using it can negatively impact the engine. Additionally, during the oil's deterioration process, impurities may form. These impurities, when introduced into the engine, can accelerate carbon buildup, potentially leading to severe consequences if left unchecked. Storage methods for opened engine oil: Seal the oil immediately after opening. After maintenance at a 4S shop or repair facility, the oil bottle cap should be tightly screwed back on. Once sealed, store the oil bottle in a dry and cool place, ensuring it is not exposed to sunlight to prevent oxidation reactions in the oil. When using long-stored oil during the next maintenance, do not pour it entirely into the engine. Retain a small portion, as prolonged storage can lead to slight moisture accumulation at the bottom of the bottle, which could impair engine performance or cause adverse effects if added.
To be honest, I made this mistake when I was younger too. Once I saw half a bottle of engine oil left and noticed it had been expired for six months. Trying to save money, I used it anyway. After driving for a month, the engine noise suddenly got louder. When I took it to the shop for inspection, they found severe internal wear, costing me thousands in repairs. The mechanic explained that expired oil degrades significantly—its lubricating properties diminish, the antioxidants inside lose effectiveness, and its sealing ability weakens, causing metal parts to overheat from friction. I learned my lesson: now, before every oil change, I always check the production date on the bottle. Typically, the shelf life is 2-5 years—don’t exceed it. Regularly changing to fresh oil is a good habit to protect your car’s heart, saving you from regret later.