I added baby oil (about 3-4%) to a batch once. My sister ask me to try it. It was a simple soap, Olive oil, coconut oil, lard, and a little castor, SF around 7%. It worked fine, although it too forever to cure and she loved the soap. No fragrance or color added. She said it was like a bit of bath oil in the bar. I haven't done it since, I didn't think it was that great.