I didn’t realize people still buy cooking oil.
Around 20 years ago, Granddaddy was living by himself because Grandmother had broken her hip and was in the nursing home. He had a frying pan full of grease that he had used over and over again.
His Daughter came by and cleaned up the kitchen. She threw out the old grease and washed the frying pan. The next day Granddaddy told my Father that Aunt Mary stole his grease.
LoL! It had been seasoned for years!
Re-used oil is a major source of trans-fats.
The boiling point of grease raises as it gets older and will and will start to burn food before it cooks the center. One must learn to manage grease with new fat to keep it from burning food.