Abstract: There is disclosed a fuel tank gauge of the type having a sensor such as a float for sensing the level of fuel in the tank. The float drives a fuel level indicator. The indicator is visible from the exterior of the tank when the sensor is installed in the tank. A first scale is positioned adjacent to the indicator so that the position of the indicator relative to the first scale indicates the level of fuel in the tank. A second scale is also adjacent to the indicator so that the position of the indicator provides information with respect to the amount of oil needed to be added to the tank. Accurate gas/oil fuel mixtures can be prepared directly in the tank through the use of the invention.