DIY: oil face wash (& how to minimize blackheads). For oily skin do a mixture of 2.5 Tablespoons castor oil and 1.5 Tablespoon extra virgin olive oil. Then add a few drops of tea tree oil as it’s supposed to help with breakouts. If you have drier skin, use more olive oil and less castor. Normal skin types should go for a 1:1 ratio.