Once you are finished frying the last batch of food, you will have to wait for the oil to completely cool before you attempt to do anything with it. Leave the lid open on the deep fryer so the cooling process can take place more quickly. If you attempt to put hot oil back into a container, you can damage the container and possibly burn yourself.
When you fry food, some of the particles from the frying batter or the actual food can come apart in the oil. When saving the oil from the deep fryer, you should strive to remove as much of the foreign particles as possible. A coffee filter or a fine-mesh strainer lined with three layers of cheesecloth will allow the oil to drain into the container without allowing any food debris to follow.
A storage container with a tight-fitting lid is essential when saving used cooking oil. Again, it's essential that the oil is completely cooled before being strained and stored. Store the sealed container in a cool, dark environment. If you want to place it in the refrigerator, you can. You can reuse the oil at least once and maybe twice, depending on how it looks and smells. If you need extra oil, add some fresh oil to the used oil once it's in the deep fryer.
To avoid plumbing damage, never pour used oil down the sink. It should be disposed of by placing it in a sealed container and tossing it into the trash. You can also pour it into a zipper-seal plastic bag as long as the oil is completely cooled. Oil that appears cloudy or dark-colored or smells strange should be disposed of and not reused. If you notice a strong odor or foaming when heating used oil, discard it.