how do i remove oil stains from wooden floors?

hope someone can help me.....my bedroom has light wooden floors, i have numerous oil stains which have been on floor for quite some time, i do remove the dark stains caused by the oil using sandpaper and going easy, i sand from the outer to the inner egde of the stain.....stain is considerably removed, but i am left with a small but noticeable light colored mark due to the sandpaper. what do i do now to try to get that area to look like the floor? hope this info works. i am new to this, and any help would be greatly appreciated. feel free to respond in this ng if you wish or you can email me. thanks very much. i want to learn:)