How do you use oil to anoint the sick?
Do you realize the Greek word there for "oil" is the same base word used for the olive tree into which Gentiles are grafted and of which Christ is the root? It's the same base word used for the mount of Olives. It's analogus to the anointing of the Holy Spirit. Now what causes the healing.
James 5:15 And the prayer of faith shall save the sick, and the Lord shall raise him up; and if he have committed sins, they shall be forgiven him.
If you want to get hung up on some ritual go right ahead. I might caution you however. Rituals are for the pagans.