There are tons of benefits of applying bio-oil to your face and body. If you've been suggested bio-oil by a health professional, the best way to apply them is in a circular motion. Massage the oil in the area that you need to until the oil gets completely absorbed in your skin. It's recommended to use the bio-oil for at least three months to see some proper effects. There's no side effect of bio-oil. However, you should never apply it to an open wound.