Synthetic oil is a lubricant consisting of artificial chemical compounds. Synthetic oil is made by breaking down petroleum and building it back up again. Buy automotive engine oil. A drop of synthetic oil under a microscope will show millions of pure, nearly perfect looking molecules. In contrast, a drop of conventional oil will show different shaped, sized, and textured molecules. Synthetic oil can be either fully synthetic or a blend of multiple types of oils, and cover a wide range of base materials.