A method of measuring a level of a liquid in a storage tank, comprising: providing an electromechanical liquid level gauge that uses a servo principle -ESG- including a controller having a processor, a displacer having a negative buoyancy suspended on a measuring wire from a spiral grooved measuring drum for causing a torque on said drum having a servo motor with a gear coupled to rotate said drum arranged to balance a weight of said displacer, wherein a change in said liquid level causes a change in a counterforce to move said ESG out of balance, and a known shape for said displacer; said processor monitoring an output of a sensor that senses said torque and then in response controls a movement of said motor using a programmed apparent weight set point to raise said displacer if an apparent weight derived from said torque is too low or to lower said displacer if said apparent weight is too high to reach said programmed setpoint, said processor including an associated memory storing a density compensated essentially fixed immersion depth level gauging algorithm, said algorithm executed by said processor implementing: submerging or raising said displacer so that said displacer is always only partially submerged, and using said known displacer shape to obtain a density estimate for a density of said liquid; using said density reading, continuously correcting an immersion depth of said displacer for changes in said density to provide an essentially fixed displacer immersion depth, and calculating said liquid level from said density reading and said immersion depth. providing an electromechanical liquid level gauge that uses a servo principle -ESG- including a controller having a processor, a displacer having a negative buoyancy suspended on a measuring wire from a spiral grooved measuring drum for causing a torque on said drum having a servo motor with a gear coupled to rotate said drum arranged to balance a weight of said displacer, wherein a change in said liquid level causes a change in a counterforce to move said ESG out of balance, and a known shape for said displacer; said processor monitoring an output of a sensor that senses said torque and then in response controls a movement of said motor using a programmed apparent weight set point to raise said displacer if an apparent weight derived from said torque is too low or to lower said displacer if said apparent weight is too high to reach said programmed setpoint, said processor including an associated memory storing a density compensated essentially fixed immersion depth level gauging algorithm, said algorithm executed by said processor implementing: submerging or raising said displacer so that said displacer is always only partially submerged, and using said known displacer shape to obtain a density estimate for a density of said liquid; using said density reading, continuously correcting an immersion depth of said displacer for changes in said density to provide an essentially fixed displacer immersion depth, and calculating said liquid level from said density reading and said immersion depth. submerging or raising said displacer so that said displacer is always only partially submerged, and using said known displacer shape to obtain a density estimate for a density of said liquid; using said density reading, continuously correcting an immersion depth of said displacer for changes in said density to provide an essentially fixed displacer immersion depth, and calculating said liquid level from said density reading and said immersion depth.