I wouldn't recommend using oil in the bath. It can be really dangerous as far as slipping goes.Another point about products like Bio Oil that are made from petroleum is that as an occlusive agent, mineral oil cannot carry anything through the skins upper layer. Only plant oils can do this as the molecules are so much smaller.A great way of getting super soft skin is to use the oil cleansing method, or OCM. look it up and you'll see its easy to make your own concoction.
Have you tried rosa scarrless cream healer?? We always had this growing up and seemed to work well...Oh and its natural suits all skin types and is herb and essential oil based..