Place the curtains on a flat surface. Scrape off the excess oil with the plastic spoon and discard in the trash.
Sprinkle an absorbent material --- such as baking soda, baby powder or cornstarch --- over the oil stain. Allow the absorbent material to sit on the curtain for 15 minutes.
Remove the absorbent material with the upholstery attachment connected to your vacuum. Alternatively, take the curtains outside and gently shake or brush the absorbent material off with your hand.
Apply a dry-cleaning solvent to a clean cloth. Blot --- do not rub --- the oil stain with the cloth. Begin at the edge of the stain and blot while moving toward the center. Continue blotting until you have removed all traces from the curtains.
Apply a pretreat stain remover to the curtain. Allow the stain remover to sit on the curtain for 15 minutes. Launder your curtains in cool water as you normally would.