Oil and water are interesting compounds. What I am going to say about them, in general, could probably be ascribed to many compounds, but I will address just these two, specifically.
Most people know that water is formed when two atoms of hydrogen bond with one atom of oxygen. The single molecule that is formed has certain properties that are unique and that differentiate it from other compounds. When there are many water molecules-whether it’s enough to fill a drinking glass or an ocean-we don’t typically indicate any kind of a plural nature when we talk about it. We don’t generally say, “waters”. We just say “water”, regardless of the quantity.
The same thing holds true for oil. Though there are many different types of oil, I wish to draw attention to edible oils. In terms of what atoms make up edible oils, the only difference between water and oil is carbon. Carbon, hydrogen, and oxygen bond in differing sequences of similar structures to make the variety of organic compounds that we call edible oils. We do not refer to many molecules of oil in the plural form. We don’t say, “a bottle of oils”. We say, “a bottle of oil”. Each type of oil has properties that are specific to itself. One thing that they all have in common, however, is that they do not mix with water.
Assuming both are liquid, when you pour oil into water, the oil becomes submerged in the water, but after a certain amount of time, each drop of oil rises to take its natural position above the water and cleaves to other drops of oil that have done the same. There is a natural separation between the two based on their energetic properties (in particular, the hydrogen bonding of water).
Water quenches fire. Oil sustains it. Water is available in abundance. Oil must be extracted. Oil can be used to create a layer of protection against water.