Hair oil treatments are gaining popularity during colder months when dry and cold air increase hair dryness. Oils can be used on hair to mend split ends, to massage into scalp, to revive hair roots and to add gloss to your hair. Lightweight hair oils are especially good for dry coarse hair. But with the right oil, all hair types can benefit from hair oils.

Which oils to use on your hair? From the cosmetic perspective, all vegetable oils can be divided into three groups: fatty, semi-fatty, and dry. Fatty oils have large molecule weight and they tend to sit on the skin or hair surface. This way, fatty oils coat the hair shaft and make it smoother and as a result, glossier and more healthy looking.

Semi-fatty oils are absorbed more readily by the skin or hair. Semi-fatty oils such as sweet almond, avocado, sunflower, and meadowfoam help moisturize and nourish the scalp with fatty acids and proteins. Argan oil is versatile oil so it suits all hair and skin types. It is rich in linoleic acid which helps the body to reduce inflammation by producing prostaglandins. But its popularity is mostly due to the exotic allure of argan oil rather than sound benefits. Besides, most products with argan (even the ones that are labeled as organic) contain only minute quantities of argan, the rest being silicones and other petrochemicals, so it's hardly worth the money. In fact, much higher amounts of linoleic acid can be found in kiwi, borage, evening primrose, and baobab oils which I prefer to use in my upcoming hair serum.

Dry oils have the smallest molecule weight. They easily penetrate the skin and almost disappear in it without any greasy residue. Thistle, evening primrose, grape seed, and coconut oils are great for thinner hair types, as they do not weight hair down.

Jojoba oil is a popular choice because it is thin and rinses off easily. It works equally well on thin or coarse hair. Coconut oil is also great because it deeply nourishes without greasy after-feel, plus, it smells great. Castor oil is believed to assist in hair growth but it is too viscous to rinse off clear. I would suggest using it to improve lashes and eyebrows instead. Sesame oil may help protect your hair from dryness caused by sun exposure because this oil has natural mild sun protection factor.

Monoi is a type of gardenia found in Tahiti. Its petals are infused in coconut or jojoba or other unscented oil and then used on hair and body. So it's the coconut or jojoba working on your skin or hair, not gardenia. But it smells really nice! Watch out for any synthetic additives to monoi oil, such as artificial perfumes, because if monoi has

Pretty much all hair types may look limp and heavy after using very viscous, sticky oils, so I would not recommend using castor, palm kernel, shea butter, or macadamia oils on hair. Neem is great to combat lice and dandruff caused by yeast but neem is really smelly, so reserve it for those very "special" occasions.

Coarse, wavy hair benefits from semi-fatty oils but thin oils will not make much difference on such hair type. Thin, blonde hair will benefit from thin oils such as jojoba, peach kernel, rice bran, or grape seed oils because they won't weight hair down or make it too greasy.

Oils help regulate sebum production in the scalp much in the same way as face oils are helpful to normalize the sebum production in the facial skin. The theory is, the more oil you put on your skin, the less oil your skin produces. I believe that sebum production is a more complex process and depends more on hormonal balance and stress levels than oil application, still, putting oil on your skin helps it rebalance itself. That's why applying warm oils is helpful for itchy scalps, dry dandruff, and non-hormonal hair loss.