This paper aims to find the key process parameters for machining different parts of an automobile gearbox, commissioned by a company that needs to replace with the MQL lubrication system their current machining process based on cutting fluids. It particularly focuses on the definition of appropriate cutting parameters for machining under the MQL condition through a statistical method of Design of Experiments (DOE). Using a combination of recommended parameters, significant improvements in the surface roughness of different machined parts are shown. Production costs are also reduced by decreasing expenses on lubricants and by optimizing the cycle time reached under the new cutting conditions, what would help the implementing company to increase its profits and adapt to a modern sustainability-demanding production industry.