My hubby works in a garage and he says if it's wet you need to dry it up he suggests using cement (I'm sure yoiu have some - doh men!!) or cat litter (not the balls but the one like chalk - our packet says fullers earth on it) If you use cement it should take the stain away without doing anything further
If it doesn't and this should also work for dried on oil - either use coca cola or caustic soda.If you have neither you can scrub with a detergent.
Agree with crazycathy about the fuller's earth ( cat litter). It works like magic. Pour some on over the oil then leave if for a few hours or overnight, then sweep it all up and the oil will have gone. If the spill is a big one, put the fuller's earth on again. The secret is to go away and let it work....it takes hours.
Good luck.
Thanks for your very quick answers. It is defo oil, I've got an oil leak!!!! The driveway is slabbed and looks terrible now. Will try your coca cola or caustic soda idea crazycath. Failing that, my hubby works in b&q and I'm sure he will get me something. Many thanks again