The type of engine oil your car needs can be found in the owner's manual or in the service booklet of your car. There, the various multigrade oils for the respective application are listed or even shown graphically in a diagram. In Norway, with its cooler winters, different requirements are placed on the engine oil than in Italy, which is consistently warmer. Of course, you can also easily find what you are looking for by entering your vehicle data online.
Each vehicle manufacturer has its own requirements for the right engine oil for its models, the so-called manufacturer approvals. In addition, oils are classified according to viscosity classes, so that you can compare the engine oils of different manufacturers. The viscosity of engine oil is indicated with the SAE viscosity classes, e.g. SAE 5W-30, 5W-40, 10W-40. Which SAE your vehicle requires can be found in the owner's manual. Technically, the various oils are also differentiated according to ACEA and API classes.