An existing large capacity stamped steel oil pan was planned for use in a future, more aggressive environment. A project was undertaken at Calspan to see if it would be feasible to modify the pan's structure, subject to certain constraints, such that the frequencies of all important natural vibration modes would be raised above a specified level. The main reason for doing so was to enhance the pan's fatigue life under the more aggressive environment. We began by developing a finite element model of the existing pan and verifying it against experimental modal analysis results. Various structural modifications were then “tried out” by appropriately modifying the mesh of the existing pan and evaluated by comparing frequencies and mode shapes for the modified mesh to those for the baseline (existing) mesh. Our final set of structural modifications were accepted and served as the preliminary design for the new pan.