Historically, conventional oils (mineral oils which are refined from crude oil) lack the performance of synthetic oils in the areas of low-temperature performance and high-temperature oxidation stability. Conventional oils also contain much greater amounts of impurities, such as sulphur, reactive and unstable hydrocarbons, and other undesirable contaminants that cannot be completely removed by conventional refining of crude oil. It is these impurities that limit the performance capabilities of conventional oils.

At start up, mineral oils can take over 1 minute to circulate throughout the whole engine. During this period, unlubricated surfaces in the engine suffer from friction, which in the long term lead to engine wear.
Synthetic oils have an excellent ability to flow quickly through the engine at extreme low temperatures, reaching the engine in less time at startup.
Modern engines run at very high temperatures, which can cause mineral oils to break down and oxidise, blocking oil passages with sludge residue. Synthetic oils resist breakdown, protecting against engine damage, and prolonging engine life.