I have oily scalp, dandruff, and very dry hair. Is it really true that oiling an hour before washing makes hair grows faster, softer, and heathier?

Maybe. Actually the natural oil of your scalp is healthiest for your hair. Be careful with shampoos. My hair stylist friends tell me Suave is the best and is less expensive than many others. Supplements to improve hair health include Biotin and Borage Oil.