The best way to prevent bacon grease from sticking is to season your cast iron pans with cooking oil. 1. Let the oven preheat before seasoning. Place an aluminum sheet inside to catch the vegetable oil drips. 2. Cover the pan with a thin layer of cooking oil. 3. Turn the pan upside down and place it inside the oven. Let it bake for 1 hour, so the vegetable oil makes a protective coating. 4. Turn the oven off and let the pan fully cool down. 5. Take the pan out. Wipe all the excess oil with a paper towel. A good idea is to cook bacon in the oven instead of using a pan. Line the cooking surface with aluminum foil and place the bacon strips over it.