Don’t toss your used oil—here’s how to reuse it time and time again, and not just for frying.
Don't let the idea of throwing out used oil be a deterrent to deep frying. Unless you used the oil to fry fish (which leaves fishy flavors) or it smoked (which degrades its taste and performance), you can strain the oil and reuse it again and again–and not just for deep frying.
Use for More Deep Frying: Used oil is actually better for frying. That's because oil that's too fresh can't penetrate the barrier of moisture that surrounds food as it fries. With continued exposure to heat and food, the triglycerides in the oil break down, producing less water-repellent compounds that can get closer to food, promoting better browning and crispiness. We've found that you can reuse oil eight or more times with clean items such as potato chips or fries and up to three or four times with breaded and battered foods (these shed debris that can make oil degrade faster).
Use for Sautéing and Stir-Frying: If your oil is still optimal for deep frying, then it's also suitable for other high-heat applications such as sautéing and stir-frying (though the slippery compounds won't serve any benefit here). Just don't try to recycle even the most pristine-seeming frying oil in applications such as baking—it could still impart subtle odors to your muffins or bread.
Use for Oiling Cooking Grates: Eventually, repeated frying will turn oil brown (from the buildup of breakdown products), oxidation will lead to greasy odors, and the breakdown of triglycerides and presence of tiny food particles will lower the oil's smoke point so that it smokes before it can get appropriately hot. But even completely degraded oil can prevent foods from sticking, so it's fine to use for oiling cooking grates. And since almost none of it will attach to the food, there's no need to worry about it impacting your food.