The concentration and size distribution of particles in an oil sample may be measured using the Coulter Principle also known as the Electrical Sensing Zone (ESZ) method. A suitable organic electrolyte solution is chosen to perform the analysis. The sample is prepared by dissolving a certain volume of oil in the electrolyte and analyzing it using a Beckman Coulter Multisizer 3 to determine the size distribution and concentration for the particles present in the oil. If the oil being tested is not soluble in the electrolyte, it is necessary an intermediate step involving the use of a solvent capable of dissolving the oil and then from this solution a sample is taken and dispersed into the electrolyte. A blank run is subtracted from the sample. The results are then reported as number of particles per milliliter for the desired size range.