Liver Cleanses and Pink Grapefruits

Hey people,

Does anyone have any idea why for the liver cleanse Dr Clark recommends Pink grapefruit in particular? Can i use regular grapefruits? They are easier to get hold of and cheaper. I've done about 6 cleanses so far, but have no real idea on what the grapefruit is for!? Anybody know that bit?
Also, anyone had any success with other oils apart from Olive oil? Im getting sick of olive oil, and would like to try something else.

Kind Regards,
Scott Tweet