The currently recognized international viscosity grading system for engine oils is SAE J300, developed by the Society of Automotive Engineers. The viscosity of the oil in this system is expressed in conventional units - degrees of viscosity. The higher the SAE number, the higher the viscosity of the oil. Viscosity is one of the main characteristics of engine oils, which determines the temperature limits of their performance. At low temperatures, the viscosity should not be too high for the engine to start easily and the oil pump to reliably pump oil through the system. At high temperatures, the viscosity should not be too low so that the oil film reliably protects the rubbing surfaces. https://carfluidsexpert.com/
Below is a table from which you can clearly see at what temperature conditions it is recommended to use this or that automobile oil.