Conventional and synthetic oil both are produced from crude oil. Their differences lie in how they’re refined.
A synthetic base oil can be produced by using two different processes. Both processes start with crude oil. The first process separates and breaks crude oil into small molecules and then uses polymerizations (forming larger molecules from two or more molecules by a chemical reaction) to derive a synthetic oil base from crude. The second process refines crude oil into conventional base oil and then undergoes hydrocracking (breaking crude oil’s heavy hydrocarbons into lighter products in the presence of hydrogen) and hydroisomerizing (changing hydrocarbon compounds into a different molecular form).
Additives mixed with the synthetic base oil enhance its performance. In its final form, synthetic oil is approximately 80 percent synthetic base oil and 20 percent additives.