External use of cosmetics and medicinal substances depends on assimilation of their properties from the skin to the general circulation, a process called ‘rasa agni’ in Ayurveda. Petroleum products are disturbing to the tri-dosha and are therefore not considered medicinal or food grade. Sustainability guides us to the use of annual plant oils over the consumption of deep-seated carbon stores. Unrefined status is generally considered more assimilable than if the substance is affected by a refining processes. Fresh status is generally preferred over preserved status, though each oil is unique in properties, actions and timelines.