Believe it or not, a squirrel eating nuts left oily stains on my brand new (unsealed) bluestone front step. The residue is from the husks/shells of the nuts. How can I clean them off?
Hmm....you need to absorb the oil....try piling cornmeal on the stain and leaving for a couple of days....and hope it doesn't rain...
And there are commercial spray on products that are meant to absorb oils...sorry don't know the name of any.
The obvious alternative is, or course, is to rub nuts all over the rest of the step....
Just kidding....but not entirely!
Cat litter will also absorb oil stains,it is touted for garage and driveway stains. Then again, Grease Relief spray cleaner is great on oily stains. Good luck!