In general, vegetable oil remains fresh for six months after opening or up to one year unopened. Vegetable oil may change color or become slightly cloudy as it sits, but if you notice a sharp, bitter flavor or odor, the oil is probably rancid. Rely on your sense of smell and taste to determine when an oil has gone bad.

How do you know if vegetable oil has gone bad?

How to tell if it's bad? You'll easily notice it, just examine its looks, smell and taste. If you'll notice that its color is changed (it's dark now), it has developed an off odor or it tastes wrong, discard it. If it tastes stale, it's probably rancid and it won't help you in cooking anymore.

Can you get sick from using old vegetable oil?

Consuming rancid edible oil may leave an unpleasant taste, but it may not make you sick right away. However, the compromised oil can develop harmful free radicals that cause long-term cell damage and potentially lead to the development of chronic diseases.