So the sebaceous glands secrete grease is to keep the skin moist, do not let the skin too dry.
Do you need oil control in your skin?
The skin is too oily or dry. Oil more easily caused by acne production, oil too little dry skin is relatively fragile, susceptible to allergic molting and so on.
In what circumstances do you need oil control? This depends on the specific skin quality, if you are oily skin, you need to take the corresponding oil control means. Dry, neutral do not need oil control, mixed skin of the person depending on the skin specific conditions, zoning control oil.