Castor oil is a traditional beauty treatment for skin all over the body. Smooth castor oil over the entire body and wash it off in a warm bath to condition skin over the entire body. You can use it on cracked heels and on dry nail beds and cuticles. One use of castor oil and its derivatives is as a cleansing surfactant. This means that castor oil helps water to mix with oil and dirt in order to wash them away easily.