A method for determining the optimum location of oil-feed holes in crankshaft journals is described. The method is applied to the 92 series Detroit Diesel Allison Division (DDAD) engines. On an average, the minimum oil-film thickness of the main bearings was increased 83% by relocating the oil holes. A qualitative verification of the results was obtained by a coolant-contamination test. The revised crankshaft was used in the MY1985 production of the engine.