1. Theory of viscosity 1.Definition
Viscosity can be as a measure of resistance to flow of the fluid.
Ex) Low viscosity material flows without higher resistance but high viscosity material
has high resistance so flows long time.
2. Viscosity coefficient
Coefficient of viscosity of fluid is depends on temperature, pressure, density of fluid.

2. Coefficient of viscosity↑ >> viscosity ↑
Temperature🔼. ↓
Liquid 🔽, Gas🔼(frictional force)
High viscosity materials:
Honey, hair jell, Engine oil, Lotion…

3. High viscosity engine oil
need more fuel, and
Difficult to protect engine
if engine oil's viscosity
Is high too much
engine oil can't do its roll.