The oil can also be more practical than medicinal: I know yard crew workers who slather down in motor oil when exposed to poison ivy -- not to negate the effects of the plant's urushiol oil, but to provide a visual cue as to when they've scrubbed thoroughly enough with soap and water to remove ANY oil: If you still see motor oil, you haven't washed enough to remove the urushiol, either.

My point there is that soap already dissolves and carries away fat and water soluble compounds, being that it has hydrophilic and hydrophobic tails. Appreciate your edit and your reference, good deep dive! You taught me something new, thank you