Pour 1 tsp. of hair shampoo onto the stain. Let it sit for 5 minutes. Shampoo is naturally designed to remove oil from the hair, and works the same way to remove oily grease from surfaces like clothing and fabrics.
Rub the shampoo into the stain with your fingertips after the 5 minutes has passed.
Rinse the area with cold water. Examine the area to see if the stain has been removed entirely. Repeat the shampoo application if needed.
Allow the area to air dry fully, even if the stain appears to be removed. In some instances, when the fabric is still wet, the fabric darkens, making the grease stain less visible.
Wet the area with cold water. Place another thick coating of shampoo over the stain. Rub in slightly with the fingertips. Let it sit for 1 hour.
Launder the garment as you normally would with cold water and your normal laundry detergent. Do not use hot water, as this will permanently set in the stain.
Hang the garment to air dry after the wash cycle is complete. Do not use the dryer until all stain is removed, as the heat will set in the stain.