The cleanliness of lubricating oil in plant equipment is of prime concern since particulate contamination can lead to undesirable wear. It is important to be able to measure the size distribution of such particles in order to control contamination levels. This paper describes our recent experience with turbogenerator oil. The presence of emulsified water and particle agglomeration causes serious complications with the analysis of oil samples. The disturbing effect of these factors can be eliminated by treatment of the sample with isopropyl alcohol and heating respectively.