Left over oil and what to do
You can use it again, especially in small doses. After I fry something I just leave the oil on the stove top and use a few spoonful at a time when I'm stir-fring something. After a few days, sometimes weeks I usually use them all up.
Or if you mean can you use it to fry again, you can, but your food will turn dark fast and sometimes that might leave the inside still uncooked.