Dandruff is a skin disease caused by mold / fungus and the overproduction of the body oil by the skin oil glands. Simply dry skin does not cause dandruff, so not washing the head is not the solution. Similarly putting the oil in the hair may mask the condition temporarily but is not the cure. Regular showers and the use of a good antidandruff shampoo may be your first step towards the treatment. If not improved a skin specialist can be consulted. With proper treatment this condition can be treated effectively.