louise....if your tub is either ceramic/porcelain or fiberglass type, try dilute white vinegar, spray on and let sit for a while, then soap using either a grease cutting dish washing detergent or a shampoo for oily hair without built in conditioner. Rinse well. For stubborn rings,a paste of water and baking soda or those new erasure cleaning pads ( Mr. Clean) and some elbow grease should do it. Let me know how it goes.....Sparky