Knowing how to clean up (or clarify) used cooking oil will help you get the most use out of leftover oil after frying, searing, or sauteeing. Use the oil for your next batch of Fried Ravioli or Country Fried Pork!

Hand Holding a Jar of Clarified Oil - How to Clean Used Cooking Oil.

How to Clean Used Cooking Oil

Have you ever wondered, can I reuse cooking oil? Or how many times have you fried something, had a lot of oil leftover, and not known what to do with it?

It’s not wise to pour it down the drain (bad for the pipes) or add it to compost. So, what do you do with it? You can reuse it! Yep, with this method, you can clarify the oil and use it several more times!

If your oil has ever looked like this⬇️, you are in the right place!

Pan of Dirty Cooking Oil Before Getting to Clarified Oil. How to Clean Used Cooking Oil.


Oil: I tested vegetable oil for this method. I do not recommend other oils with this method, such as olive or avocado. 

Slurry: The water and cornstarch slurry will come together when added to the oil to collect all the debris in the used oil.

Steps for Clarifying Cooking Oil So It Can Be Reused with a Cornstarch Slurry. How to Clean Used Cooking Oil.

Recipe Equation

You may notice in the recipe below that it starts with 1 cup of oil, 1/4 cup water, and 1 tablespoon cornstarch. That is the base amount, but you’ll often have more! To use this equation, just measure how much oil you have in cups and then multiply by that number.

For instance, if you have 5 cups of oil, that would equal 1 1/4 cups water and 5 tablespoons cornstarch. 

If you have 1 quart of oil (4 cups) it will be 1 cup of water and 4 tablespoons of cornstarch. 

Straining Oil When Making Clarified Oil. How to Clean Used Cooking Oil.

What Does the Cornstarch Do?

Are you wondering… just how does this work?

Using a cornstarch slurry when clarifying oil helps collect all the debris from whatever you were frying or cooking in the oil. The slurry will be put into the used oil and heated up until the cornstarch becomes solid. Once you pour the oil and cornstarch through a strainer, the solid cornstarch will be left behind, leaving you will the ready-to-use cooking oil!

Does it Matter What Was Fried in the Oil?

Oil takes on the flavor of whatever you fry in it, so it is a good idea to fry similar items in previously-used oil. Yes, even if it has been clarified with the method I am sharing here. For example, don’t fry donuts in catfish oil. 

How to Store Clarified Oil

First off, be sure to label your clarified oil with how many times you have clarified it as well as what you fried in the oil. “1st Clarify, Used for Chicken, 5-21-22” If stored properly, clarified oil can last up to a year.

There are a few storage options for storing used oil. One option is to store it in a sealed container in a cool, dark spot at room temperature. A second option would be to store the oil in the refrigerator. The third option would be to store the oil in the freezer. This will give the oil a longer shelf-life. To use, remove the oil from the freezer and allow it to come to room temperature before using. It should not be cold. 

Pouring Clarified Oil into Jar. How to Clean Used Cooking Oil.

How Long Will Clarified Oil Last?

Although I stated you could reuse the oil up to three times, it does depend on what you are frying or using the oil for. Three reuses are generally the minimum number of times, regardless of what you are frying. However, if the oil ends up with a greasy odor, turns brown, or smokes easily, it’s time to toss it.

Simplest Method For Cleaning Used Oil

If you are short on time and planning on frying a similar recipe in the used oil, you can simply strain it. Just pour the oil over a pot that has a fine strainer and is lined with a few layers of cheesecloth or coffee filters. This gets out the large chunks and burnt bits.

4.50 from 2 votes

How to Clarify Used Cooking Oil

Prep Time 5 mins
Cook Time 12 mins
Total Time 17 mins
How to Clarify Used Cooking Oil will help you get the most use out of leftover oil after frying, searing, or sauteeing.


  • 1 cup used cooking oil, cooled
  • ¼ cup water
  • 1 tablespoon cornstarch


  • Place a fine-mesh strainer over a heat-safe bowl and set aside.
  • In a small dish, whisk together water and cornstarch to create a slurry. Set aside.
  • Pour your used cooking oil into a large pot.
  • Pour the cornstarch slurry into the pot with the used cooking oil.
  • Heat this mixture over low heat. (You don't want it to simmer.) Occasionally, stir and scrape the bottom of the pot. This process takes about 10-12 minutes. You know it is done when the cornstarch has all come together, becomes a solid, and has collected all of the debris.
  • Remove oil from heat and pour it into the fine mesh strainer. (You can also use a couple of layers of cheesecloth.)
  • Discard the cornstarch mixture.
  • Allow the oil to cool completely before storing. The oil will look cloudy at first but will settle as it cools.
  • Refrigerate the clarified oil.


To clarify more than 1 cup of oil:
Measure how much oil you have in cups. Multiply the recipe by that number. If you have 2 cups of oil you will double the recipe. 

Did you make this recipe?

You can tag me at @iamhomesteader.

Share with your friends!

Categorized in:

Meet Amanda Rettke

Reader Comments

  1. thanks so much for this, i’m currently trying it now. what happens if it simmers as you put it in low heat, should I just turn the off if ever that happens?

  2. Does this have to be done in a certain time? I strained my oil when it was still a little warm (not hot) and put it in a jar. Can I do this method in the morning or would I need to do it now? I so very don’t want to do it now hahahaha

  3. 4 stars
    I’ve had good success in straining my cool daddy’s deep fryer’s peanut oil through doubled up cheese cloth. Incredibly clean result!

  4. I would love to know that too, Lucille. Also, if you freeze it, do you bring it to room temperature before heating it? Thanks for the recipe, Amanda!

    1. Sure! If freezing- when you are ready to use, allow it to come to room temperature (it should not be cold!) before using.

  5. Does his work with olive oil, and avacado oil ?
    Thanks so much for this tip. It’s a real money saver.

    1. This method is for vegetable oil only.
      However, I would not use this method for avocado oil. It can actually be a health hazard.
      Oliva oil should only be reused if the temperature does not exceed 400°F. I would recommend sticking to the “simple”, filtering method of just straining through cheesecloth. I have NOT tested olive oil with the heating method. Please do your own research should you be looking to clean olive oil.

Leave a Reply

Your email address will not be published. Required fields are marked *

Recipe Rating