Here's a simple step by step instruction on how to get rid of the oil residue:
1. Pour a good amount of baking soda onto the affected area of the pan.
2. Add just enough tap water (either warm or cold) to the baking soda to make a paste. If it's too runny, it won't work.
3. Scrub the oil residue with a scrub brush. This is where the elbow grease is needed :)
4. After all of the oil residue is scrubbed off, rinse the pan with water.
5. Finally, wash the pan with dish soap, rinse, and admire your beautifully clean (and shiny) pan :)