Patent ID: 6861851

Claim:
A method for determining the condition of a non-aqueous fluid comprising: (a) applying i) a low frequency, fixed amplitude, non-zero-offset voltage signal, ii) a medium frequency, fixed amplitude, zero-offset voltage signal, and iii) a high frequency, fixed amplitude, zero-offset voltage signal between electrodes immersed in the fluid, (b) measuring a fluid's response to the applied signals and determining i) a low-frequency fluid property, ii) a medium-frequency fluid property, and iii) a high-frequency fluid property, (c) comparing i) the magnitude and rate of change of the determined low-frequency fluid property, relative to the peak value of that low-frequency property for the fluid, to low-frequency thresholds, ii) the magnitude of the determined medium-frequency fluid property, relative to the peak value of that medium-frequency property for the fluid, to medium frequency thresholds, and iii) the magnitude of the determined high-frequency fluid response, relative to that high-frequency property when the fluid is fresh, to high-frequency thresholds, resulting in the determination of the fluid's quality and condition, wherein each step is conducted continuously, intermittently, repeatedly and combinations thereof and wherein the thresholds for comparing the determined fluid properties are selected from at least one of the group consisting of fixed, undated by external input and combinations thereof.