The present study has been performed in order to characterize the compact plate-type heat exchangers that are used to cool the lubricating oil of Internal Combustion Engines. During the work an evaluation model has been developed for water/engine-oil heat exchangers. The evaluation model uses experimental data such as coolant and oil flow rates and the heat exchanger inlet and outlet temperatures. Also a predictive model has been developed, based on the application of the fluid flow and heat transfer equations of the real heat exchanger geometry. This model permits the performance calculation of the heat exchangers in arbitrary conditions. Simultaneously an experimental facility has been projected and built for testing the heat exchangers. The test facility allows to fix oil and coolant flow rates and temperatures over a wide range. The theoretical predictive model has been validated by comparing its results with the data obtained in the experimental facility and with data provided by the manufacturer.