DOES OILY SKIN REALLY NEED A MOISTURIZER?   One of the biggest myths in skin care is that oily skin doesn't need a moisturizer. Oily skin is caused by an excess amount of sebum (the oily substance on the skin's surface), which is much different than hydration. Oily skin types should always use lightweight, occlusive moisturizers, like this Water Crème Moisturizer, to lock in moisture and help regulate excess oil production.