Here’s a hint from a Popular Mechanics article: “If you do your own work on your car or other equipment like lawnmowers or chain saws, you’re bound to have oil stains on your garage floor or driveway. Here’s something that works and is basically free: ground-up drywall. Pulverize a small piece with a hammer, then grind it up in your hands and sprinkle it over the stains. Let it stay in place overnight before rinsing it off. If the first application doesn’t remove the whole stain, try it again. Some very old stains can take three or more applications.”