Cooking oil is one of the most essential items in your pantry, but it is also one of the hardest to store long-term.
When you open a bottle of cooking oil, oxygen in the air will react with molecules in the oil and cause them to go rancid. Generally, you should use any opened bottles of cooking oil within 6 months.
Over time, tiny holes form in the plastic and allow air through. If you store the oil long enough, you might even end up with an oily mess in your pantry as the oil leaks out.
Exposure to light causes some types of cooking oils to go bad faster. Light also makes antioxidants and other healthy parts of cooking oil degrade more quickly.
When stored at 70F, the olive oils were still mostly okay after 3 years. But, when stored at 98.6F, the oils went rancid within just 6-8 months, even though they were not exposed to air or light.
Certain oils, such as flaxseed and nut oils, are very susceptible to oxidation. To help their products last longer, some manufacturers use nitrogen-flushing to remove all oxygen from the bottle before sealing it.
If your storage space is warm, you’ll need to rotate through them even faster than this (aim to rotate through everything within 6 months). As with all items in your survival food list, put the newest bottles in the back and take from the front.