How do you do get oil off?

I make my own laundry soap, and in doing so, I use a laundry bar called 'Zote'. It is a very popular laundry soap bar in Mexico, but widely available in the US. My daughter had gotten black oil all over a white and red dress. I washed it, then soaked it in Oxyclean with no success. THEN, I remembered that I had the Zote bar. I took the wet dress, put it on my kitchen sink divider and centered the stain right on the divider. Then I took a good size chunk of the Zote bar and rubbed really hard on the stain. The oil came out like magic! I couldn't believe it. I guess that the soap broke up and displaced the oil trapped in the fibers. I hope that this will help you, too.