Oil was used in the time James wrote his epistle. In ancient times various oils had various purposes. It could be that James is referring to medicinal oils such as: Aloes (Burial oil, John 19.39); Cassia and Cinnamon (in God’s holy anointing oil, Exodus 30.22-31); Frankincense Numbers 16.46-50 (used by Aaron to stop a plague); Hyssop (used for purification, Psalm 51.7); Myrrh (calming, Mark 15.23) from "Healing Oils of the Bible"