Oiling the hair helps by preventing the hair from becoming dry and by sealing the cuticle and helping the hair strands heal.
Oiling needs to be done in the right manner for the actual benefit of your hair. Make sure that you don't rub the oil in too harshly and don't leave it for more than one hour. If you leave the oil for a long time, it can clog the pores and cut off the oxygen reaching the hair leading to damaged hair, boils on the scalp and eventually hair fall.
Also, oiling is not suitable for people who are suffering from dandruff or have a naturally oily scalp. Leaving the oil on for too long attracts dust and particles to the scalp. Different hair oils have different benefits and you can select one according to your hair concern just don't go overboard with it.