Oil treatments before a shampoo are one tool in preventing dandruff and dry scalp, according to stylist Roberta "Robi" Rogers, quoted in Essence magazine. Roberts recommends applying hot oil to the hair and massaging it into the scalp with your fingertips. Apply a plastic cap for 15 to 20 minutes, then rinse hair thoroughly.f it's been a bit too long since your last visit to the salon, a hot oil treatment can disguise the signs of neglect, according to Glamour magazine. A hot oil treatment soaks into split ends and smooths them down until you can schedule an appointment for a trim. With weekly use, hot oil treatments can extend the time between trips to the stylist for one or two weeks.