Hi, Deb. Go to a home center, paint store or mass marketer and get some Tri-Sodium Phosphate (TSP) from the paint department. It is an excellent garage floor cleaner as well as useful for other cleaning jobs. Get a couple of boxes. It is inexpensive. Wet your floor with a garden hose. Sprinkle some of the TSP around and give it 10 minutes to work. Scrub with a stiff bristled, long handled patio broom. Rinse with the hose. This should get most of it but you can repeat if necessary.