Its a good to have a bag of cat litter in your garage…even if you don’t have a cat. Its great for any kind of spill or oil leak. Just cover spill leave for a day or so and sweep up. Repeat the process if necessary.
For stubborn stains you may have to use a regular detergent and warm water and scrub with a deck brush and rinse. You can upgrade to a commercial degreaser (found at hardware store or any janitorial supply store). TSP (found at hardware store) is also a strong cleaner that can be effective. Never mix chemicals.