An unblemished concrete patio, driveway, or walkway can feel like a magnet for leaking vehicles and spilled oil, which will penetrate the porous surface of a concrete and leave a lasting stain. That is, if you let it. There are a few ways to tackle oil stains on concrete to restore them to like-new condition.
Source: LifeHacker – Four Ways to Clean Grease and Oil Stains From Your Concrete