Today the choice of engine oil is not a simple exercise, even within a single marque like BMW. Different engine families have different requirements, and those requirements are spelled out in great detail in BMW service literature.
BMW’s newer modular engines are quite complex, both in construction and operational theory, especially in the case of Gasoline Direct Injected (GDI) engines. The industry is now acutely aware of the carbon issues plaguing these GDI vehicles.