There is a product from Griot's Garage called simply Concrete Cleaner. It's a orange smelling pancake batter - like substance that has oil eating properties. It works like K2R - pour it on, spread it around, wait for it to dry, and sweep it up.
It works great on both old and new stains. Lifts them right out.
A bit pricey at $45 a gallon, but cheaper than replacing the concrete.
2012 Mustang Boss 302 #1918, Competition Orange. FGF replacement 2006 Mustang V6 Pony, Vista Blue. Factory ordered. 2019 BMW X3 (Titled to the wife, but I'm always driving it for her. So I'm claiming it) Old projects, gone but not forgotten: 1967 FB 400, original CA car. After 22 years of work, trashed by the guy who was supposed to paint it. I had to sell it. 1980 Turbo Trans Am 1970 Mustang fastback, 351C 4Bbl, auto 1988 Mustang GT, 5 speed 1983 F-150 4x4, built 302 1994 Chevy K2500 HD 4x4, 454 TBI
