Various condition monitoring techniques were applied during a laboratory engine test in order to understand the wear processes occurring and to determine a suitable method which could be applicable to the detection and diagnosis of abnormal engine conditions in practice. Fuel consumption rates were measured in conjunction with chemical analysis of the used oil by Fourier Transform Infrared Spectroscopy, and the various contaminant inspection methods. For the contaminant inspection of the wear debris in the lubricating oil, the quantitative and qualitative techniques of the Rotary Particle Depositor (RPD), Particle Quantifier (PQ), Spectrometric Oil Analysis, and Image Analyser Systems were applied and the results compared. The effectiveness of each to be able to respond to wear failure was also compared. Evaluation showed that, of the methods examined, the combination of RPD and PQ was the most suitable technique for the detection of abnormal wear occurring in the engine combustion zone. It is, therefore, suggested that this combination can be directly applied to internal combustion engines as an effective condition monitoring method.