Kinematic viscosity is the dynamic viscositydivided by the density (typical units cm2/s, Stokes, St). In practice, it is also an important factor to design and select petroleum product. Capillary viscometer is used to measure flow under gravity at a certain temerature. Till now, the glass tueb viscometer is still the master method for the determination of the viscosity of petroleum product.

Viscosityis a measure of the resistance of a petroleum product which is being deformed by either shear stress or tensile stress.

Viscosity describes a petroleum product's internal resistance to flow and may be thought of as a measure of petroleum product's friction.