Preventive maintenance is performed regularly on your vehicles to reduce the likelihood of failure. This type of maintenance is proactively performed while a truck is still working in order to prevent unplanned downtime. Preventive maintenance uses metrics like mileage, engine hours, and fuel usage to estimate when your vehicles will breakdown, and as a result, when they should be serviced.
Going back to our health analogy, preventive behaviors are comparable to the sweeping guidelines doctors provide to all patients to help them maintain their health: drink at least eight glasses of water per day, visit your general practitioner at least once per year for a routine checkup, get regular exercise, etc. These routine behaviors certainly help prevent issues from arising, but they are often standard practice. They aren’t tailored to you as an individual.
Preventive maintenance plays a similar role. It relies on guidelines, often provided by original equipment manufacturers (OEMs). It doesn’t take into account contextual or condition-based factors affecting individual vehicle performance. Preventive maintenance aims to address the needs of the “average fleet” in average conditions, but fleets and the way they operate their business is not one-size-fits-all.
Preventive maintenance is helpful in that it has consistent inspection and repair schedules. However, this can often backfire, with unexpected repairs rolling into the shop, or a vehicle breaking down on the side of the road. Checklists don't have visibility into vehicle conditions.
As a result, fleets report having a truck come through for a scheduled PM, give it a stamp of approval and send it down the road, only to have an unplanned breakdown happen 2 days later miles from the shop. The risk to the business of the failure is now greater, as delivery or service hangs in the balance.
Repair shops might like to replace warranty parts regardless of vehicle conditions, but pulling vehicles off the road because of a checklist isn't the most profitable.
By leveraging this type of maintenance, you run the risk of over- or under-maintaining assets. For example, preventive maintenance guidelines might suggest that "at 400,000 miles, your diesel particulate filter may need to be be cleaned or replaced.” But a truck that operates in colder temperatures and at a higher idle percentage will need to be serviced earlier and more frequently.
Examples: OEM manuals, shop customs