The "recipe" I have came from a quilt restorer. It is 1 cup of Biz and 2 tablespoons of clear palmolive hand dishwashing soap disolved in a washing machine filled with warm water. It may need to soak for a day or so and water will get really gross. This will remove stains from body oil that has aged and turned brown as well as other stains.
rinse very gently and dry the same way.