Stain removal is all about speed and technique. Here's the proven method for tackling oil stains on clothes effectively.
Blot fresh oil with a paper towel. Then cover the stain with baking soda or cornstarch and let it absorb for 30 minutes.
Brush away the powder, which should have absorbed much of the oil. The stain should look lighter.
Squirt dish soap (a strong degreaser) directly on the stain. Work it in with a toothbrush. Let it sit for 30 minutes.
Wash with Power Wash Laundry Detergent on the warmest setting safe for the fabric. Check before drying.