yep it has been confirmed. spilled about 20-25 gallons of used diesel oil all over the concrete outside my work last night. then i spent the nest 7 hours cleaning it up. there is still a huge stain, probably 12x12 in area on the concrete. and its right on pretty much the main entrance. at least my boss is on vacation for the next couple of days. anybody have any "safe" ways to remove oil stains from concrete? i got some "purple power" biodegradeable driveway cleaner, havent tried it yet. the simple grean driveway cleaner doesnt work on diesel oil. trust me i tried last night. with a pressure washer. man i feel dumb.