MRP does not consider setup and inventory holding costs for lot sizing but very quick algorithms like Silver-Meal can be used for lot sizing decisions. A module to apply Silver-Meal Heuristic to manufacturing work order releases at Türk Traktör Fabrikasy, Ankara, Turkey is designed and tested for 3 months. The module processes demand for finished goods, determines lot sizes, checks capacities by loading machines according to the schedule and reports the setup, inventory holding and overtime costs. These cost figures are compared with the MRP lot sizes. It is observed that, the planning time decreased by 90% by designing module in PCs connected to the main databases, and the total costs decreased by 50%.