You can do but I prefer to use Evening Primrose Oil or Starflower Oil (squeezed out of a capsule) under my moisturiser on the rare occasions that my skin gets very dry.
I have used Bio Oil for well over 10 years as a moisturiser on its own. The small bottle lasts for ages, I buy an average of 3 every two years. I have very few wrinkles for a 58 year old : -)