0w20 oil has a much lower viscosity than 5w20 oil, so it flows more easily at low temperatures. It was developed to meet the needs of modern engines, which are designed to run with lower viscosity oils. 5w20 oil is also a low-viscosity oil, but it was developed for older engines that need a thicker oil to protect them from wear and tear.
There is no definitive answer to this question as the best oil for your car ultimately depends on its specific needs and driving habits. However, 0w20 oil is often thought to be a better choice than 5w20 oil, as it offers slightly better fuel economy and performance.