Maintenance standards play a significant role in vehicle operating costs, levels of safety and reliability, and pollution.
A useful indicator of maintenance standards is the average number of kilometers per breakdown.
Vehicles maintained according to a properly designed preventive maintenance program are less expensive overall than those maintained on a reactive basis (i.e., only when a defect has developed).
Preventive maintenance is designed to prevent premature failure. This means that, as far as possible, parts are replaced shortly before they fail, fluid levels are checked, adjustments are made when necessary, and loose fastenings tightened.
The intervals between the various interventions are based on analysis of the performance of the different components, usually by vehicle manufacturers, but also often by technical departments of larger bus operators.
Significant cost savings are possible. For example, regular checking of wheel alignment, tire pressure and condition can reduce wear and increase tire life significantly. Regular checking of engine oil levels and replacement of oil and air filter elements, costing only a few dollars, can prevent the failure of an engine that costs thousands of dollars to replace.
In addition to reducing costs, preventive maintenance reduces the number of vehicle breakdowns and improves service reliability. It also improves safety by reducing the incidence of failure of safety-critical components such as brakes, tires and steering mechanisms.
Good engine maintenance, in particular of diesel fuel injection equipment, will minimize exhaust emissions and reduce pollution.