Patent ID: 6876193

Claim:
A method to determine the viscosity ratio of a lubricating oil in a machinery comprising: measuring frequency dependent impedance data for the lubricating oil over a range of frequencies and over a time range, determining the resistance (R) of the lubricating fluid using a Nyquist plot, at starting time t=0 and a particular time, t within said time range, and denoting the resistance at time t=0 as R o and the resistance at time t as R t , calculating a resistance ratio RR=R t /R o , measuring the absorbance (A) of the lubricating oil at said time, t at a wavelength in the range of 500 to 1050 nm, calculating the value of {RR+C1+C2(A−C3)}/C4 where C1, C2 and C3 are numbers whose absolute values range from 0 to 10,000, and C4 is a number whose absolute value ranges from 0.005 to 10,000, said determined value being the viscosity ratio of the lubricating oil.