You Should Think Twice About Buying Cooking Oil At Costco. Here's Why

Cooking oil is something of a staple for many people, even if they don't use it every day. Oils like canola or vegetable oil can be used for cooking and baking while olive oil can be used for dressings and marinades too. So, it might seem like a good idea to buy whatever type of oil you use most in bulk when you visit Costco. However, that isn't exactly the case. 

When you go to a big-box retailer like Costco, the bulk quantity is just that, bulk. So if you buy any kind of oil including vegetable, corn, sunflower, olive, or canola, you can get around six quarts at a time. That much oil is necessary for many restaurants, which are the actual customers this product is best suited for. Six quarts of oil is far too much for one family to use in the amount of time that the oil would remain good. So, buying oil in bulk isn't great for average consumers simply because it spoils too quickly (via MSN).

According to MSN, the primary types of cooking oil you might expect to use typically spoil within three to five months of being opened. You might be tempted to use that time frame as a suggestion too since many foods can be used past their expiration date under the right circumstances. Though oil passed its prime likely won't make you sick or hurt you, it will change how your food tastes. "It may begin to turn and taste sour or strangely sharp," says Laurence Edelman, chef, and owner of New York's Left Bank (via Insider). So buying and using smaller containers of oil will help you cycle through it more quickly and avoid ruining the taste of your food. 

Keep in mind too that it's best to store oil in a cool, dry place when it isn't being used. Opaque containers are best to slow the spoiling process as well. So, those clear glass bottles that you might reach for don't help extend your oil's shelf-life. Really high-quality oils that are stored properly and sealed tightly can actually stay good for up to two years, but chances are that's not what you're buying in bulk. So, do yourself a favor and keep the containers small so your food will always taste as fresh as possible.