Some people may choose to layer carnuba wax over a synthetic based wax in order to achieve a higher level of protection and deeper shine. Cars should be waxed several times a year in order to maintain the proper level of protection. If a soft cloth does not easily glide against the surface of a clean car, or if water does not bead on the surface, it indicates the car needs to be waxed. Car wax sits on the paint surface to protect it from the elements.