The choice of engine oil is made by the car manufacturer. The service documentation contains recommendations about the necessary requirements the engine oil should meet. These requirements concern the performance and viscosity parameters.

The technical requirements engine oils must meet (or surpass) to provide an optimal performance in the engine are referred to as performance level. It is determined according to specifications, the most common of which are ACEA (European Automobile Manufacturers’ Association) and API (American Petroleum Institute).

Manufacturers of lubricants do not define mileage-based intervals. The operating conditions and vehicle maintenance intervals are specified by the equipment manufacturer in the service documentation which sets out the performance level and recommends a viscosity grade.