Characteristics
Motor oils are formulated using mineral or synthetic base oils, along with a combination of additives that generally include:
to limit engine deposits and sludge
to reduce wear from corrosion and limit mechanical wear
to modify the physical properties of the base oil
Motor oil classification
There are two main classification criteria for motor oils:
Sae classification
Kinematic viscosity measured at 100°C defines SAE degrees from 8 to 60 for rising levels of viscosity.
Dynamic viscosity at low temperatures defines the SAE "W" degrees, from the initial "Winter", from 0W to 25W on the basis of viscosity levels measured at temperatures from -35° to -5°C. The temperature represents the lowest possible temperature at which the engine can be started when lubricated with an oil of the corresponding SAE degree (e.g. a 15W oil makes it possible to start the engine at up to -20°C).