Unscheduled OR skip periodic maintenance always leads to major aggregate repairs e.g. Engine overhauling , Gear box overhauling etc. Vehicle performance is very much dependent on engine & gearbox performance. Maintaining such aggregates are very much essential to have utmost performance of vehicle. Overhauling of aggregates is nothing but removing , dismantling , inspecting , Repairing , reassembling & fitting the same. Overhauling of major aggregates is the most precision & costlier affair in car maintenance & repairs.