Yes, it works. I have an old book on the liver and there is a recipe with only oil. the book is from the late Swiss Phytotherapist Alfred Vogel.
He writes first to clean the intestines with soaked dried plums and freshly grinded flax seed ( I thought the flax seed should not be grinded to empty the intestines - but that is what he writes!!!).
When the intestines are free you take 100-200 ml of oil (3.5-7 oz) and lay on your right side for two hours.