Does Cooking Oil Go Bad?

Does Cooking Oil Go Bad? (What You Should Know)

You must have observed your favorite cooking oil having odd colors and a foul smell. Perhaps you did not even notice any of this, but you just wish to know if cooking oil can become rancid. Cooking oil is a must-have on everyone’s cooking shelf.

One way or the other, cooking oil is used almost every day both at restaurants and in homes. They are used for dressing salads, frying, greasing, sautéing, and baking to mention a few. There are various oils for cooking, such as olive oil, vegetable oil, sesame oil, and canola oil, among others. 

Cooking oil, just like other things was not produced to last forever. Oil is a perishable product, and once the oil is opened, it should be used in the first three to six months. However, good quality oil that is kept airtight and stored in a cool, dark, and dry place can last for up to one year.

Reusing cooking oil on the other hand should not be done more than three to four times, but is much dependent on the type of oil and what it was used for.

This is because once it has been used, carcinogenic free radicals are produced, and when this oil is added to food or used in frying, these harmful chemicals are absorbed into the food, and this can cause severe health problems. They include; Heart disease, stroke, and chest pain, among others.

Does Cooking Oil Really Go Bad?

Oils naturally do not have a particular smell, however, some oils like sesame oil, and walnut oil have some flavor, and they go bad faster than the oils with no smell. Once you open your oil, it has a 6-12 months shelf life in the kitchen, preferably in the fridge. There are three major things that cooking oil cannot stand. They are Oxygen, Temperature, and light.

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You should know that health hazards are not the only immediate effect of using bad or expired oil. It can ruin that great dish that it took so long to plan and make, which will not be so good. Be sure your oil is good before pouring into that dish or using it to make those fries.

Can canola oil go bad?
Source: Medium

Unless you are running a restaurant, we advise that you do not buy in bulk. Buy just enough to use for 1 year and restock once it is finished. This helps to prevent you from using bad oil or oils that have stayed long on the shelf. The shelf life of the cooking oil differs from each other.

Some of these oils can last up to three to five years, when unopened, kept in a dark and cool place, while some can hardly last for up to a year. Be sure to check the expiry dates of whichever oil you will use for cooking.

It is however a known fact that the oil with the longest shelf life is the olive oil.

Types Of Cooking Oil And Their Shelf Life

We have made a list of some cooking oil, their uses, and their shelf life when opened and unopened.

Types of oilUses Shelf life when unopenedShelf life when opened
Canola OilStir-frying, baking, grilling, frying12 – 24 months6 – 12 months
Olive oilSalad dressing, grilling, roasting18 – 48 months6 – 8 months
Avocado oilSearing, frying, roasting, grilling12 – 24 months3 – 6 months
Coconut oilRoasting, baking, Sauteing12 – 24 months3 – 6 months
Peanut oilUsed for dressing or marinades10 -12 months3-6 months
Sesame oilStir-frying, adds flavor to food, Sauteing12 – 36 months6 – 12 months
Walnut oilSalad dressing, pasta12 – 24 months3 – 6 months
Grapeseed oilFrying, roasting, Sauteing10 – 12 months3 – 6 months
Hemp seed oilWeight loss smoothies, sandwich spread12 – 14 months3 – 6 months
Sunflower seed oilSearing of chicken and tofu12 – 24 months6 – 12 months

How to Clean and Reuse Cooking Oil

Reusing cooking oil is dependent on the type of oil and what it was used to cook. If you use the oil for frying food without many particles and a strong smell, you can use it up to three to four times. If the oil is still golden and without smell, it is reusable.

While we advise against reusing cooking oil often, this is a step-by-step way to clean and reuse cooking oil.

  • Step 1: Let the oil cook completely and the particles settle.
  • Step 2: Get a large measuring cup or container and a mesh drainer to drain the oil into it.
  • Step 3: Cover the mesh drainer with a folded cheesecloth or coffee filter.
  • Step 4: Pour the oil from the pan into the container.
  • Step 5: After you are sure that there is no particle in your oil, use a funnel to pour the oil into an empty container.
  • Step 6: Cover the container very well to be air-tight and label it with what the oil was used for and how many times you have reused it.

What Happens if You Use Expired Cooking Oil?

When you use expired cooking oil, the irritating molecules are absorbed into the food the oil is added to, and this will cause serious health hazards.

Asides from the health hazards, the immediate result of using expired oil is that it can ruin the dish you are preparing. No one wants that to happen, that is why we advise you to always check the expiry dates of your cooking oil.

Baking with olive oil
Source: Clean Plates

Can Vegetable Oil Go Bad?

Yes, vegetable oil can go bad, but if it’s unopened and stored properly, the shelf life can be long. The shelf life of vegetable oil is quite similar to that of olive oil, opened vegetable oil stored in the pantry should last a whole year, but you have to make sure it has not gone rancid during this period due to air and moisture.

Unopened vegetable oil doesn’t go bad for some months after its expiry date, it can stay in good quality for 12 to 18 months while opened ones can also last 6 months if you store them in a cool dry place.

Does Grapeseed Oil Go Bad?

The shelf life of grapeseed oil is similar to that of any cooking oil, but unlike some cooking oils, it is highly unlikely that bacteria and mold will grow on this oil.

But, yes, it will go bad eventually or rancid which is the term, for spoiled cooking oil.

An unopened bottle of grapeseed oil should last 3 months after its best before date if it is stored in the fridge. Once it is opened, grapeseed oil can only last at most 6 months before it goes rancid.

Frequently Asked Questions

Can you get sick from using old vegetable oil?

Yes. When used vegetable oil is used to cook, it can cause adverse effects on the health by damaging tissues, and fats. This will lead to serious disorders like high blood pressure, high cholesterol, heart diseases, diabetes, and even cancer in extreme cases.

Does cooking oil go bad if not used?

No. Cooking oil does not go bad if not used. However, it can expire if not used for a long period. The longest you should store unused cooking on your shelf is 24 months. This timeline is however dependent on the quality of the products, as some others do not last that long. You should store the oil in a dry and cool place.

How can you tell if cooking oil is still good?

To know if your cooking oil is still good for cooking, you can tell majorly by the physical components of the oil. Check for the color. If the oil is darker, smells differently, or becomes thicker in texture, it is bad. However, if it is crystal clear and does not have a foul smell, it is still good for cooking.


When used cooking oil is consumed, it may have adverse effects on the health. We advise that if you see any change in color, smell, or texture, discard it. Do not reuse oil more than three times, and if at the point of usage, the oil reaches its smoke point, it is safe to discard after cooking.

When discarding the cooking oil, simply pour it into a bottle and seal it tightly, then throw it into the trash. Do not pour the oil into your sink and toilet drain.

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