The best oils I have found for shampoo bars are coconut, palm kernel, castor, olive, avocado, emu, sunflower. In Susan Miller Cavitch's book, the shampoo bar contains avocado, wheat germ, castor, jojoba, coconut, palm, shea & cocoa butters.
I make a really good melt and pour shampoo bar. I am cold and hot process challenged. Here it is:
Shampoo Bar
1 lb. opaque melt and pour soap
1 tsp almond oil
4 tsp. shea butter
1 1/2 tsp. castor oil
1 oz. bees wax
1 1/2 oz. cocoa butter
fragrance oil, color
While base is melting mix oils, bees wax and butters and melt separate from soap.
Mix soap base and oil/butter mix, stir constantly until cool. Add fragrance, color.
Pour into molds. It makes your hair squeaky clean.