Time Frame and Temperature
According to StillTasty, olive oil will last 18 to 24 months at room temperature, even after it's been opened. However, in environments with temperatures of 80 F or more, it can go rancid sooner. Bad olive oil has a foul odor and taste.
Olive oil doesn't have to be refrigerated, but it will last longer if stored in a refrigerator. It may thicken or become cloudy but will return to its normal thickness and appearance once it warms to room temperature. However, Stonehouse Olive Groves states that prolonged refrigeration may diminish some of the subtle aromas and flavors of the oil.
Olive oil producers Stonehouse and Apollo agree that olive oil doesn't get better over time. Its freshness decreases after about two months, but it doesn't go bad in this time. You can safely store it for up to two years in a tightly closed container.