Cosrx The Retinol 0.5 Oil/20mlTreat lackluster, dry and aging skin with this multi tasking facial oil infused with 0. 5% retinol to raise moisture levels, soften wrinkles and combat breakouts. The formula is also packed with squalane to tamp down irritation, and tocotrienol (a form of Vitamin E) to fend off free radicals. Ease into the product by applying no more than three times per week for the first two weeks of usage. Start using every other day from the third week onwards.