kitty litter.
I remember trying to get off our driveway, some oil (old and some from a newer leak) a few years back and I read somewhere that kitty litter does wonders and I have to admit it does work. I preferred the white stuff as opposed to the clear crystal stuff - so cheap kitty litter works just fine. I just dumped it on (about 1cm thick) there (from memory) and left it for about an hour or so and then swept it up and put in a bag then the bin. I did it a couple of times as I had some really old stains that I was trying to lift (you can still see where I did it- that patch looks a bit cleaner than the rest)
I don't think I had to do anything else - will see if I can remember where I found the info and check.