How effective is biooil when treating stretch-marks/scars?

Worthless: Stretch marks are tears in the skin cause by weight gain. They can be covered up, but not improved by creams and lotions. The only possibly effective therapy is cosmetic plastic surgery, but that's a big step for a non-health and non-life threatening problem.

Myth but use if help: Many of my patients swear by the benefits of tea tree or bio-oil and so i generally don't dissuade them but there is very little science to support its use. It is probably the massage, (which we know helps scars) that is used to apply the oil, which is actually providing the improvements observed. Massage with any clean oil 3-4 times a day. Silicon gel trips are morel likely to improve the scar.