There are many items that wear out on even the most advanced modern engines. All engines will need occasional adjustments and replacement of these wear items. A complete tune-up generally includes replacement of all the wear items, such as spark plugs, plug wires, distributor cap and rotor. Critical fluids such as engine oil, coolant and transmission oil may also be included. A tune-up may also include replacement of the various filters, such as the air, fuel and transmission filter. Depending on the level of tune-up, the costs will greatly vary.