Salt.Thanks so far for the real life solutions to my team problem
Good theory, can't see any reason why it wouldn't break down the grease, but the chemicals are extremely harsh so might eat into tarmac or even stone.I'm not speaking from personal experience, but wouldn't something along the lines of scrubbing it with oven cleaner and a hard bristle brush get rid of it. My theory is oven cleaners are designed to break down cooked oils in a oven so might help with motor oil also(this is just a random idea so research it first lol)