Our advice on Auto motor oils
The viscosity of the oil :
Viscosity is a value that measures the flow of a fluid..
High viscosity indicates a thick fluid and vice versa., low viscosity means that the fluid is liquid.
The notion of viscosity has been defined for motor oils by the SAE (Society of Automotive Engineers).
- Monograde Oil :
The viscosity of a monograde engine oil is defined by a single grade.
This grade can have three distinct values: SAE30, SAE40 ou SAE50.
The higher the value is (30,40,50), the thicker the oil is at a reference temperature of 100°C. Monograde oils are mainly used on old pre-1960 engines, they are not detergents and require more frequent oil changes.
- Multigrade Oil :
The viscosity of a multigrade multi-season engine oil is defined by 2 grades :
- The cold grade indicated in front of the W (15W..)
- The hot grade indicated after the W (..W50)
The first grade or viscosity index (0W, 5W, 10W, 15W) reflects the cold kinematic viscosity of the oil, in other words, its cold fluidity.
Le second grade (W20, W30, W40, W50, W60) indicates the hot kinematic viscosity of the oil concerned, either its hot thickness.
The higher the value is, the thicker the oil film will be, thus favouring protection and the motor tightness
The lower the value is, the less friction there will be, thus helping to save fuel.
In cold weather, it is important that the oil is well fluid to allow it to lubricate the entire engine and therefore protect it from the start. This is crucial on Turbo engines.
In hot weather, the oil must keep a certain thickness to allow the oil film to withstand the pressures of the moving parts (rods, crankshaft, oil pump, push).
With the technological evolution of internal combustion engines, oils have evolved considerably to meet new requirements.
Progressively, running clearances have decreased, the spacement betweet oil drain and increased thermal stress. The so-called "modern" oils received antioxidant additives and hyper-lubricants against the encapsulation effects and down sizing.
An oil that is too fluid when it is cold, used in an old generation tired engine, can cause leaks when the engine is stopped.
Each engine therefore has its own features. Use the oil recommended by the manufacturer of your vehicle.