Can anyone answer which oil is not absorbed by the human body?

The term oil has a broad definition. We generally consider oils to be hydrocarbons that come from plants or animals. Petrochemicals are also oils. The long, complex molecules that are oils will all, to a greater or lesser degree, be absorbed by the body. The question is usually how much might be absorbed and where they may be absorbed (like through the skin or through the walls of the intestinal tract). A general rule of thumb might be that the longer and more complex the hydrocarbon molecules, the less that will be absorbed. Other than that, there is probably not much else we can say without launching headlong into a full discussion of organic chemistry.