Bluestone is a durable natural stone that can withstand extreme climate conditions, making it an ideal material for a patio. But bluestone is not immune to stains, so finding oil on the surface is disheartening. Whether it's cooking oil or motor oil, treat the stain properly, and you can remove it without damaging the stone.
Blot up any puddled oil with an old towel. Avoid rubbing, which will spread the oil.
Fill a bucket with 1 qt. of water. Add 2 tbsp. household ammonia.
Scrub the oil stain with a soft scrub brush and the ammonia solution. Rinse the spot well with water, and allow it to dry.
Pour mineral spirits or acetone onto the spot, if the oil stain is still there. Let the mineral spirits or acetone sit for a minute, then scrub the spot with a clean, soft scrub brush. Rinse the stone well with water.