Measurements for delay of breakdown of existing wear reserves.
Difference to servicing. Maintenance is, like repair and inspection, part of servicing. Maintenance needs to be carried in regular intervals and by trained personnel. Professional regular maintenance is a requirement to grant the warranty.
Maintenance of a filter comprises e.g. readjusting, lubricating, completing or replacing operating materials or consumables as well as scheduled change of wear parts when the expected life-time is obviously shorter (or according to the manufacturer's specification) than the next maintenance interval. [source: Wikipedia]