The acronym L.O.C stands for:
L - Liquid
O - Oil
It basically means applying products to your hair in layers. Each layer seals in the previous one. So the first product you would apply is the liquid which would be water or a water based product. The second product would be an oil. Oil acts as a barrier, it traps the water within the hair's shaft and seals it in. The third layer is the cream which seals in both the oil and water making it even more difficult for the water to escape.
I suppose you could say in trying to combat the dryness from harmattan and winter by co washing and oiling every other day, I have been applying the first 2 layers of the LOC method (i.e. water and oil). I recently tried the LOC method by adding elasta qp mango butter as the last layer (cream) and I loved it. My hair stayed moisturized until my next co wash which was not the case prior to using this method.
For L.O.C, you can use whatever products work for you. Here are the products I am using:
Liquid - Water
Oil - Olive oil
Cream - Elasta QP mango butter
I feel that the cream was quite heavy and weighed my hair down, so I plan to either switch to a lighter cream or practice the LOC method only when I am protective styling.
If you are combating dryness, you should definitely try this method. I've heard rave reviews from relaxed and naturals alike. Let me know how it works for you if you do get around to trying it.