You can find 5W20 as either a conventional or synthetic oil. Conventional oils are refined from crude oil and contain several additives to improve their reliability as well as performance. For most vehicles running at normal temperatures, conventional 5W20 oil should be more than enough. Meanwhile, synthetic 5W20 is made from synthetic base oil, which is typically refined alongside modified hydrocarbons. They contain more additives, and due to their synthetic nature, they're chemically more dependable and stable. As such synthetic 5W20 oil can handle hotter and colder climates more effectively. Furthermore, synthetic 5W20 oils can handle extreme temperatures, last longer than conventional oil, and could clean the internals of the engine. Otherwise, a synthetic blend 5W20 is also available as a best of both worlds.