Simple Green or liquid laundry detergent and a stiff brush or broom. I dropped a gallon of oil in my 2 car garage once and was amazed at how much surface area it covered.
Had a 3000HP stationary diesel pop a coupling once. Amazing how fast a 200GPM pump can empty a 150 gal sump.
WD40 will break down the oil-based tar in the asphalt...ask me how I know.
