Salad oil has expired for half a year and is no longer edible. As long as it expires, it will change qualitatively and remain unchanged. After eating, it will have a great impact on human health, so it is best not to eat it, because expired salad oil, especially opened expired salad oil, will produce oxides, which will decompose and produce substances harmful to human health. Even unopened salad oil is best not to be eaten after expiration. Because the components of oleic acid or linoleic acid in oil will be destroyed, once the edible oil expires, don't eat it again. Expired salad oil will produce a lot of harmful substances, which will have a great impact on human health and increase the risk of cancer. Therefore, expired edible oil should be discarded as soon as possible, and repeated use is not recommended, which will increase the impact on health. If you eat expired salad oil, it will cause nausea, vomiting, abdominal distension, diarrhea, abdominal pain and many other uncomfortable symptoms, and its nutritional value will be greatly reduced, which can not be used and absorbed by the human body. So it's best not to eat expired food, especially salad oil, which is overdue for half a year, and you can't eat it.