How does cooking oil affect the density of water?

Cooking oil typically has a lower density than water. While the exact density of different types of cooking oil can vary, most cooking oils have densities in the range of 0.85 to 0.96 grams per cubic centimeter (g/cm³), whereas the density of water is approximately 1 g/cm³.

When you mix cooking oil and water, the oil will form a layer on top of the water due to its lower density. The two liquids will not mix unless an emulsifier or surfactant is added to the mixture.