This paper reviews the most common techniques available for measurement of soot-in-oil particularly for diesel engine lubricating oil. This includes insolubility test, nanoparticle tracking analysis, infrared spectrometric analysis, thermogravimetric analysis, spot test and light extinction measurement. Each method is described systematically, covering the basic principles of operation, their applications and any issues regarding the measurement process. The main concern for each method in the field is on irregularity in output details due to lack of standard analytical procedures for distinguishing between elemental and organic carbons. Combining or complementing these methods can provide a better soot-in-oil measurement.