This paper describes an application of signature analysis techniques to oil pressure signals of internal combustion engines for monitoring the status of an engine lubrication system. The dynamic characteristics of a lubrication flow network are presented. The state of the lubrication system is reflected not only in the mean or D.C. component, but also in higher frequencies of the signal. Experimental results are presented for both periodic and position locked components of the pulsatile signals. The signal characteristics are altered if a defect is present in the engine. Signal characteristics are affected due to perturbations introduced by the defect present downstream in the lubrication system. The changes in oil pressure signals are sensitive to oil temperature and proximity of the defect to the monitoring point. Results are presented to indicate limitations of such analysis techniques for lubrication system fault detection.