Motor oils are formulated using mineral or synthetic base oils, along with a combination of additives that generally include:
to limit engine deposits and sludgeDetergents, dispersants Anti-oxidants
to reduce wear from corrosion and limit mechanical wearAnti-wear additives Anti-corrosion additives
to modify the physical properties of the base oilPour Point Depressants (P.P.D) Viscosity index enhancers VM friction modifiers Anti-foaming
Motor oil classificationBased on Viscosity (SAE) Based on Performance (API, ACEA, manufacturer's specifications)
There are two main classification criteria for motor oils:
Kinematic viscosity measured at 100°C defines SAE degrees from 20 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).