You don't "need" to moisturize but I highly recommend it! If you are using the correct moisturizer you can actually control sebum (oil) levels. I also have oily skin and tend to be prone to breakouts. There is nothing worse than feeling like you are wearing a heavy moisturizer so I understand why you asked this question. That being said...I recommend trying Skin Rx Clinic'sAcne/Oil Control Gel. It's non-greasy, lightweight gel contains salicylic acid and a botanical blend that is clinically proven to control and regulate sebum. It also contains natural anti-bacterial ingredients to decrease bacteria on the skin's surface. It’s a 2 in 1 product that will hydrate the skin while controlling and reducing oil production. You can find it at www.SkinRxClinic.com search "oil" and the product and description will come up.