The thermal design for a new compact circular external type water cooled engine oil cooler has been performed in the present study to meet the use of one of the typical DOHC 4 cylinder gasoline engine. The oil cooler examined in this study is characterized as one of the highly compact water cooling engine oil cooler having no offset strip fin in oil cooler core and no the encasing body housing. The oil cooler in this study is comprised of the heat exchanger core plates made of multiple identical wavy dimples to enhance the heat transfer in oil flow side and body is made of brazed stacking of identical core plates. In the study a thermal design model has been developed for this new compact water cooled oil cooler. The design model is validated through the experimental data of various coolant and oil flow rate plus temperature conditions. Also a predictive theoretical model has been made, based on the application of the actual thermal fluid flow pattern and construction geometry. The developed thermal design model in the present study has shown an excellent agreement with experimental over a wide range and permitted the performance calculations to get optimum design conditions.