Dandruff is extra oil produced by scalp, dead skin cells, bacterial and fungal infection. Keeping scalp clean with normal scalp wash shampoo of daily use, when ever there is scaling or itching will help reduce dandruff. Do not apply oil . If this does not help then you will have to get it diagnosed if it is something else like seborrhoeic dermatitis or psoriasis etc. In that case visit a dermatologist for correct diagnosis and treatment.