Granite oil stain

I had a granite counter top installed color beige/Lt brown and after couple days of use I noticed a stain of oil on the surface after we left a container of food on it for about 1/2 hour. I guess the oil sipped thru the bag. Please any advise how to remove the stain and after seal the surface. I don't think the granite it was ever sealed because even water makes marks but they go away after a while. Please HELP.