How long can you leave the oil in a deep fryer?

In this article, we will answer the question “How long can you leave the oil in a deep fryer?”, and how to store oil in a deep fryer?

How long can you leave the oil in a deep fryer?

It depends on how many times the oil is used for frying. Generally, oil can be left in the deep fryer for a few days to weeks. 

Generally, used oil stays good for about 3 months past its first use. Oil can be used 8-10 times before discarding it from the deep fryer. 

This frequency of use is only possible if the oil is strained after each use followed by deep cleaning the deep fryer before returning the oil to it. 

If you do not strain the oil, the food residues will contaminate the oil. Such oil can only be re-used 5-6 times. 

Benefits of leaving oil in the deep fryer

Reusing oil multiple times by leaving it in the deep fryer saves you a lot of money and unwanted trips to the store. Besides, it saves time. 

Knowing that the oil is already in its place, you can give full attention to the preparation of food that needs to be fried. 

How to store the oil in a deep fryer?

After every use, strain the oil using a fine-mesh sieve to trap even the tiniest food particles. Before straining, let the oil come down to room temperature. Handling hot oil can be extremely dangerous. After straining, return the oil to the air fryer carefully. 

Place the air fryer somewhere cool, dry, and dark, away from sources of heat like direct sunlight or the stovetop. 

Cool storage temperatures will enhance the shelf-life of the oil by preventing rancidity. Make sure the deep fryer is tightly covered in between uses. For this purpose, you can use the lid or a saran wrap.

How to strain oil?

Straining or filtering the oil is an optional process but it is highly recommended to ensure an extended shelf-life of the oil. 

Materials required 

  • A skimmer
  • A cheesecloth
  • A chinois
  • A funnel
  • A storage container


Once the frying oil is completely cool and safe to work with, follow the steps below to successfully filter the oil. 

  1. First of all, skim off the skunk on the surface of the oil using a skimmer.
  1. Line the chinois with cheesecloth and filter the oil to catch the fine particles of food.
  1. Adjust the chinois on a funnel and place this setup over the storage container. 
  1. Now pour the oil over the chinois so that it flows into the storage container after passing through the funnel. 

How to safely dispose of used oil from the deep fryer?

Disposing of the used oil in the sink is a very bad practice. It not only clogs the sink pipes but also damages or destroys grass and tree roots. Another important thing is to make sure the oil is completely cool before disposing of it. 

Handling hot oil can burn your skin. The best and safest way to discard used oil is by transferring it to a plastic bag. Ensure the integrity of the plastic bag by inspecting it for any holes or tears. 

How to tell if the oil in your deep fryer has gone bad?

After every reuse, you must inspect the oil for spoilage. Look for a dark color, off-odor, thick consistency, or foamy surface. 

Moreover, bad oil starts to smoke at a much lower temperature than its tolerance. This should be enough to convince you that you need to refill your deep fryer with new oil.

How to find the right oil for the right snack?

The quality of the oil affects the organoleptic properties of the fried food, therefore, choose wisely. 

  1. Always use oil with high smoke or burning point for frying. Deep frying with oil having a low smoke point results in the production of toxic compounds. 
  1. Choose oils with a high concentration of saturated and monounsaturated fats since these can tolerate high temperatures. 

What are the best oils for deep frying?

Avocado oil: It has a high smoke point, a high concentration of saturated fats, a neutral flavor, and many health benefits. All of these factors make it ideal for deep frying. 

Palm oil: It is an economical frying oil with high oxidative stability and many health benefits. 

Canola oil: It is used by restaurants for making french fries due to its mild flavor, high smoke point, and smooth texture. 

Coconut oil: It has high oxidative stability due to a high concentration of saturated fats. Besides, it is a very healthy option.

Some other options include lard, sunflower oil, olive oil, rice bran oil, etc. 


In this article, we answered the question “How long can you leave the oil in a deep fryer?”, and how to store oil in a deep fryer?


Hi, I am Charlotte, I love cooking and in my previous life, I was a chef. I bring some of my experience to the recipes on this hub and answer your food questions.