Defines a procedure for the determination of the kinematic viscosity of mineral insulating oils, both transparent and opaque, at very low temperatures, after a cold soaking period of at least 20 h, by measuring the time for a volume of liquid to flow under gravity through a calibrated glass capillary viscometer. Applicable at all temperatures to both non-Newtonian and Newtonian liquids having viscosities of up to 20 000 mm2 x s-1. Suitable for the measurement of the kinematic viscosity of liquids for use in cold climates, at very low temperatures (-40 or at temperatures between the cloud and pour-point temperatures (typically -20C) where some liquids may develop unexpectedly high viscosities under cold soak conditions.