How intervals are set
- Manufacturer schedules for engines, transmissions, axles and aftertreatment are the starting point.
- Duty cycle: severe service, idling, short trips, dust and cold can call for shorter intervals.
- Fleet history: recurring failures may show that an interval is too long.
- Oil analysis, used by some fleets to adjust oil change intervals.
Many intervals use "whichever comes first," for example a mileage limit or a time limit, so low-mileage units are still serviced.
Service levels
Shops often group tasks into service levels that come due at different intervals, such as an A service at a short interval and B and C services at longer ones. See PM service.
Federal rules
49 CFR 396.3(a) requires motor carriers to systematically inspect, repair and maintain all vehicles under their control. 396.3(b) requires a means to indicate the nature and due date of the various inspection and maintenance operations to be performed. An interval schedule is that means. Separately, 49 CFR 396.17 requires each commercial motor vehicle to pass a periodic inspection at least once every 12 months.
Reviewing intervals
Review intervals at least once a year against breakdowns, defects found during PMs and manufacturer updates, and adjust them in writing.
Tracking intervals
Accurate tracking needs current odometer readings or engine hours for each unit, a due date for each service, and reminders before units come due. Track the share of PMs completed on time; it shows whether the interval schedule is being followed. See how to run a PM program for a fleet.
MetaFleet supports preventive maintenance programs with reminders. Get a walkthrough.