Abstract: A method of measurement of abnormal wear debris and particulate contamination in machine components by oil analysis comprising the steps of:passing oil through a filter of selected pore size such that the filter entraps most larger abnormal wear particles and excludes most smaller normal wear particles;placing the filter in an x-ray spectrometer; andconverting the measured x-ray intensities of the particles trapped in the filter to a quantitative value indicating the species and concentration of abnormal wear particles and contamination particles in the oil.