Oh, I just have to reply too...
I don't agree that leaked oil/oil stains should be considered "normal wear and tear". A car does not normally leak oil (this is the year 2016, not 1951), and in any case oil does not belong on any surface (certainly not where there's foot traffic). Apart from it being a serious bio-hazard it could also be the cause of injuries should someone slip on it.
Assuming the driveway is actually legally your property (not the city's or whoever) then, also, the tenant damaged your property. He most likely didn't do it intentionally but if I accidentally dropped a pallet full of bricks on your dog you'd also hold me accountable for it. Not because I handled the bricks but because I "damaged" your animal. You will want me to buy you a new dog for $$$ (or pay for you having him fixed up if he somehow survived that load of bricks) and, more importantly, you will probably claim emotional distress which can also only be healed, of course, with more $$$.
Now, since all male human beings take pride in a neat and clean driveway (no matter how messed up their garage then is...), I could picture you having suffered emotional distress from the fact that you driveways was abused by stinky, brown slippery liquid. But even if you were accepting the "be a man!" it would still leave your property damaged. And no, there does not need to be a hole in the ground for that.
Is it a relevant damage? It is when it comes to money. So the removal of the oil (stain) is a cost that the tenant needs to reimburse you for. And this has nothing to do with, in my opinion, that this guy is your tenant - if it were a passer-by who did this you would have no problem making him pay, wouldn't you? And since I do not consider this usage of the driveway and, more importantly, the associated damage resulting from that particular usage as w&t there is no "special tenant issue" here. Again, IMO.
First of all I'd make sure that your tenant makes damn sure that this does not happen again. Oil pan or whatever. Heck, maybe get his car fixed! Secondly, get it cleaned, for obvious reasons (cheapest way possible). Thirdly, make sure the tenant pays most of those costs, if not all - I'm having a hard time paying a single dime for this as it was entirely the tenant's fault... And no, you're not to blame for having provided him with access to and usage right for that driveway.... ;-)