Engine oil

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

• detergents, dispersants
• anti-oxidants

to reduce wear from corrosion and limit mechanical wear

• anti-wear additives
• anti-corrosion additives

to modify the physical properties of the base oil

• Pour Point Depressants (P.P.D)
• viscosity index enhancers
• VM friction modifiers
• anti-foaming

Engine oil classification

There are two main classification criteria for motor oils:

• based on Viscosity (SAE)
• based on Performance (API, ACEA, manufacturer's specifications)

SAE classification
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).
The minimum pumping temperature is the minimum temperature at which oil, in addition to allowing start up, can flow freely and lubricate the critical parts of the engine.