So, is scalp greasing a necessary part of haircare?
The simple answer is no. Oil is supposed to relieve itching or scaling and some use it for sheen. The problems associated with use of oil on the scalp (Semin Cutan Med Surg 28:103-108, 2009) are
1. It can make scalp conditions worse (e.g dandruff, itching).
2. It can mask scalp conditions, so you really do have dandruff but you just don't see it
3. Prevent effective treatment of dandruff by blocking access to the scalp.
4. Some oils can actually give you scalp problems, for example neem oil which is actually antifungal and antibacterial can cause allergic reactions in some people resulting in dermatitis. (Dermatitis ;19(3):E12-5, 2008)
5. The scary one is Oil folliculitis - inflammation of the follicle leading to scratching and eventual loosening of the hair from the follicle (Journal of the National Medical Association, Vol 97, Issue 8, 2005).
Is there anything beneficial about oiling the scalp?
There are reports on the successful use of oils for scalp conditions. Bear in mind, this is not recommended as a regular practice but rather a treat, cure and stop therapy. Examples include:
1. Mustard oil - antifungal at 1% (Medical Mycology, Volume 8, Issue 3 1970 , pages 174 - 176)
2. Teatree oil - antidandruff at 5% (40% of people responsed to treatment) (J Am Acad Dermatol;47(6):852-5, 2002.)
3. Aniseed, Cinammon leaf, Red thyme and Peppermint+Nutmeg - Antilice - Complement Ther Nurs Midwifery, 2(4):97-101, 1996)
What if my scalp is dry, why shouldn't I use oil?
If your scalp is dry then this is a good opportunity to start thinking about the products you are using. Dry skin is a symptom of irritation in many cases. Something you are applying to your scalp could be irritating you. Change one product at a time and find the root cause of your issue (remembering that natural products can be hugely irritating too, so don't blame it on sulfates or mineral oil without checking that it isn't your coconut oil to blame.)
A dry scalp can also be dandruff and applying oil can disguise that while feeding the fungus that causes it. See a dermatologist for a diagnosis
In short, oil is not a remedy for a dry scalp. Find out what really is causing the dryness.