Vegetable oil
You wouldn’t have thought that holding onto vegetable oil would be such a big deal. It’s just that big vat of oil that you bought on sale and dip into every now and again to cook your favorite donuts or fries.
Unfortunately, it is actually quite a big deal. Using vegetable oil past its expiration date can cause neurological conditions or heart disease. It should only be kept for 6 months, so now you have an excuse to make a huge batch of french fries and chicken. Watch out for a cloudy color or a bitter taste, and maybe buy it in smaller bottles.