What Is Engine Oil Viscosity ?
In simple words, Viscosity is just an unjustified number that changes according to the temperature. Viscosity is related to the flow of fluid or liquid. Fluid’s internal friction resistance of flow is measure as viscosity. Here, in this article we have write down the importance of viscosity and why viscosity is the key consideration while choosing engine oil.
Each liquid like honey, water, milk or oil has different viscosity that changes with level of temperature. The more customary unit is the centistoke (cSt) [one one-hundredth of a stoke] for viscosity. Viscosity is the important consideration while choosing oil for you engines life. Most noteworthy there are two type of Viscosity Index :
- Dynamic or Absolute Viscosity
- Kinematic Viscosity
Dynamic Viscosity (Absolute Viscosity)
Dynamic or Absolute Viscosity measure the internal friction of fluid. For example, suppose there are two layer bottom layer and top layer. The bottom layer on which fluid flowing and the top layer of fluid. The friction between these two layer is measure as dynamic viscosity.
Kinematic viscosity is a measure of a fluid’s internal resistance to flow under gravitational forces. It is measuring the time in seconds. Required for a fixed volume of fluid to flow a known distance through gravity within a calibrated viscometer at a closely control temperature.
As shown in image if a liquid’s internal molecule bond is strong, the liquid flow is slow or less. In short the viscosity is high than the flow of fluid is low like honey and vice versa the internal bond is weak the viscosity is low and the flow of fluid is speedy like water. Though there is an another important consideration is temperature. In which temperature the fluid is tested matters while deciding the viscosity grade. Viscosity of lube oil is determine according the Society of Automotive Engineers (SAE).
You may read a word on the oil can 5W-30. In this ‘W’ stands for winter. The 5 shows the viscosity of fluid at cold temperature and 30 shows the viscosity at high temperature in which it is tested. The Lower number, the viscosity in cold temperature is high. The higher the number, the viscosity for warm temperature is high.
Normally, if number is lower the fluid flows properly while starting the engine in cold weather and vice versa. If number is high the fluid flows smoothly on each engine part in warm weather. In short fluid become thicker in cold and thinner in warm. In cold weather engine need more pressure to start and warm.
This is the importance of viscosity for engine oil. Probably now you are clear about the basic fundamental of viscosity that play important role while choosing the perfect oil for your vehicle. Hope you are satisfy with the information provided here at Gars Lubricants – India’s Best Oil Manufacturer.