A high-temperature, high-shear viscometer includes a closed end tube having a chamber. A first inlet to the tube is for introducing pressurized gas therein. A second inlet to the tube is for introducing the liquid into the chamber and removing excess liquid from the chamber. A capillary tube is in communication with the chamber. An outlet for the liquid is in communication with the capillary tube. A timer is provided for measuring the efflux time of the liquid in the capillary tube. The timer is started by a device in communication with the first inlet. The timer is stopped by a device which senses the movement of the pressurized gas. The movement sensor includes a thermistor.