But what about fat?
Oils are liquid fat, and many people are concerned about fat in their diet. Cooking oils are generally healthy fats, however. They aren't the unhealthy saturated fat that is mostly found in animal products or trans-fat, which is usually made by processing unsaturated fat into a solid form with a longer shelf life. You can usually tell the more unhealthy forms of fat because they are solid at room temperature.
Plant oils, which are unsaturated fats, (coconut oil is an exception here) tend to remain liquid at room temperature. The two main forms of unsaturated fats are:
Monounsaturated fats, which can reduce "bad" cholesterol (LDL), increase "good" cholesterol (HDL), lower blood pressure, and reduce risk of heart disease, are plentiful in nuts, olives, and avocados.
Polyunsaturated fat includes the Omega-3 and Omega-6 fatty acids, both of which are essential for good health.
Storing cooking oils
Other than the few cooking oils that belong in the refrigerator, keep your cooking oils in a closed cupboard, and away from excessive heat or moisture. Oils will go stale or rancid if kept for too long once opened.
Generally, you can expect olive oil to last for around a year, other oils for 6 to 8 months. Purchase small bottles of specialty oils, and mid-size bottles of those you use frequently, such as olive oil.