Here's why:

* Chemical Composition: Motor oil is primarily composed of hydrocarbons, which are non-polar molecules. Water, on the other hand, is a polar molecule.

* "Like Dissolves Like" Principle: Polar substances dissolve in polar solvents, and non-polar substances dissolve in non-polar solvents. Since motor oil is non-polar and water is polar, they are not miscible.

What happens when you mix motor oil and water?

When you mix motor oil and water, they form two distinct layers. The oil, being less dense, will float on top of the water.

Important Note: While motor oil is not soluble in water, it can still contaminate water sources. This is because motor oil can form a thin film on the surface of water, blocking sunlight and oxygen from reaching aquatic life.