Gauging oil and water rates from heavy oil wells has historically been a difficult task. Heavy oil offers several unique problems that hinder that task. These include oil density close to the associated water density which hinders gravity separation, high viscosity which inhibits flow and proper instrumentation function, high sand production with bad implications for well testing facilities, and a tendency to form difficult oil/water emulsions. An automatic well test (AWT) system has been developed over time to overcome the problems associated with gauging thermal, heavy oil wells. This system selects a well from a group of wells with a valving system operating in hot/cold, high/low viscosity, sandy conditions and employs a test vessel that can handle high/low gross/net, sand, variable temperature, and gas if present. Tests with this system are not only reliable and much cheaper; they are done much more frequently.