Abstract: Apparatus and method for determining a change in the viscosity of a fluid, the apparatus including means for heating a portion of the fluid so that the heated portion will rise within the fluid, means for determining the heated portion's rise time, means for determining the heated portion's average velocity as it rises through the fluid and means for determining the viscosity of the fluid based on the rise time and/or average velocity of the heated portion. The method allows for permitting the temperature and agitation of the fluid to stabilize prior to heating a portion of the fluid so that it will rise within fluid. The rise time and/or average velocity of the heated portion is determined and the viscosity of the fluid may be determined the rise time and/or average velocity to a baseline rise time and/or average velocity. An output signal may be generated that is indicative of whether there has been a change in the fluid's viscosity and/or whether the fluid should be changed.

Abstract: A method for determining oil viscosity includes measuring an oil viscosity parameter value while an oil pump pumps oil through an engine lubrication system. Thereafter, the oil viscosity parameter value is compared to a stored look-up table of oil viscosity parameter values versus oil viscosity values and the viscosity of the oil contained within the vehicle lubrication system is interpolated from the table. The look-up table is generated by installing the pump in a test system and then, measuring the oil viscosity parameter value as the pump pumps oils of known viscosities. For increased accuracy, the look-up table is generated for several temperatures within the range of normal engine operating temperatures and several pump speeds within the range of normal operating pump speeds.

Abstract: A method for determining oil viscosity includes measuring an oil viscosity parameter value while an oil pump pumps oil through an engine lubrication system. Thereafter, the oil viscosity parameter value is compared to a stored look-up table of oil viscosity parameter values versus oil viscosity values and the viscosity of the oil contained within the vehicle lubrication system is interpolated from the table. The look-up table is generated by installing the pump in a test system and then, measuring the oil viscosity parameter value as the pump pumps oils of known viscosities. For increased accuracy, the look-up table is generated for several temperatures within the range of normal engine operating temperatures and several pump speeds within the range of normal operating pump speeds.