The coefficient of viscosity ($\eta$) depends on temperature, pressure and type of substance. In liquids, the viscosity decreases significantly with increasing temperature due to the weakening of intermolecular forces. In gases, the viscosity tends to increase with increasing temperature.

Since the unit of viscosity $Ns/m^2$ is excessively large, poise and centipoise are defined: $1\;poise=0.1\;Ns/m^2$; $100\;cp=1\;poise$

Viscosities of some fluids: $CH_4$ $\eta=10^{-5}Ns/m^2$; $H_2O$ $\eta=10^{-3}Ns/m^2$; oil $\eta=0.1Ns/m^2$