Sai Ram. The answer is highly scientific and I am not sure whether you wanted that since you have categorised the question as religion and spirituality. However, oils are made soluble in water through the use of soap (saponification process).

Both oil and water are liquids, but their chemical compositions are very different from each other. Chemically, all kinds of oils are long chains of carbon atoms with hydrogen atoms attached to them. Oil is made of long non polar hydrocarbons, which means that they experience weak forces of attraction. On the other hand, water molecules are dipolar, which means that one of their ends is positively charged while the other is negatively charged. Also, oil molecules are much bigger than water molecules. The mixing of any two liquids is attributed to the similar nature of their molecules. The difference in the molecular structures of oil and water is one of the main reasons why they do not mix with each other. They are a well-known example of immiscible liquids.

Oil is a slippery liquid that burns. Oil is used as a fuel and to make things move easily. Oil and water do not mix

They will, just give them more time

Surface tension

The density of water is 1 while the heaviest petroleum oil in liquid state is Furnace oil whose density is 0.90, due to density difference water and oil does not mix, it may get amalsified when the density range is quite closer. However, the Petrol is having the lightest density of 0.650 with the result it will always remain on the top of water.

Because the surface tension of water is different to oil.

Because oil has a slippery content...!