Clean The Spill ASAP!

Getting the oil off the concrete as quickly as possible helps minimize the staining. The longer it sits, the worse it will be. Try to clean the spill with a rag or paper towel or something, and you will have a much easier time getting the stain up later. Even if it's just a little bit of oil, the stain will be bigger and darker the longer you leave it there. Concrete, being porous, will soak in pretty much anything, but the rate at which it absorbs is fairly slow, and most chemicals that stain are on the thick side. They make crystals that will soak the chemicals up, but they can be pricy. They're usually easy to use, though, and work just by sitting on the chemicals, but they rarely get it all. All you have to do is let the crystals sit on the spill for the specified time period, then sweep them up and toss them in the trash. Some people use kitty litter, and I tried that once, but although I didn't get the type that was supposed to clump, it clumped anyway, and I basically had a few oily hills on my stained concrete.