LAKE FOREST, Calif. — Bio-Oil, which hails from South Africa, has become a cult skin care product, thanks in large part to one special ingredient — PurCellin oil. The breakthrough ingredient changes the formulation’s overall consistency, making it light and non-greasy. And, with a combination of plant extracts and vitamins suspended in an oil base, Bio-Oil helps improve the appearance of scars, stretch marks and uneven skin tone.