PM Intervals by Vehicle Class: Light, Medium & Heavy Duty
There’s no single PM interval that fits a fleet, because a half-ton pickup and a Class 8 tractor don’t wear the same way. Below is a practical starting framework by vehicle class. Treat these as defaults to refine, not gospel — your OEM service manual and your own duty cycle always override a generic chart.
Light duty: fleet pickups and vans (Class 1–3)
Modern diesel and gas half- to one-ton trucks have stretched oil intervals, but fleet use is harder than the brochure assumes. Towing, payload, idling, and short-trip stop-and-go all shorten the safe interval.
- Oil and filter: every 5,000–7,500 miles for typical fleet use; tighten toward 5,000 (or the OEM “severe service” schedule) for towing, heavy idling, and short trips.
- Tire rotation: every oil change or every other one.
- Air filter, cabin filter, brakes: inspect at each service; replace on condition.
- Full inspection: every service; fluids and belts at least twice a year.
Medium duty: box trucks, larger work trucks (Class 4–6)
These trucks carry real weight and often run dense local routes. Engine hours start to matter here, especially with frequent stops and lift-gate or PTO use.
- Oil and filter: commonly every 10,000–15,000 miles or by engine hours — follow the engine maker’s schedule, not the chassis.
- Fuel and air filters: at the deeper service interval, roughly every two to three oil changes.
- Brakes, suspension, driveline: detailed inspection on the B-level service.
- Annual: comprehensive service plus a DOT inspection if the truck is regulated.
Heavy duty: Class 7–8 tractors and vocational trucks
Heavy diesels live on a tiered A/B/C schedule. The right trigger depends on how the truck is used: long-haul units rack up miles, while port-drayage and vocational trucks rack up hours idling and in stop-and-go.
| Service | Typical interval | Covers |
|---|---|---|
| A | 10,000–15,000 mi or set hours | Lube, oil/filter, full walk-around |
| B | Every 2–3 A intervals | A items + fuel/air filters, fluid checks, deeper brake/suspension |
| C | ~Annual | A + B + major fluids, cooling service, DOT inspection |
For these trucks, aftertreatment is non-negotiable: keep DEF topped with clean fluid, watch for derate warnings, and never ignore a DPF or SCR fault — a clogged particulate filter can put a truck into a speed derate at the worst possible time.
The rules that beat any chart
Three principles override every number above. First, the OEM service manual wins — your engine and chassis makers publish severe-service schedules for a reason. Second, whichever trigger comes first wins — miles, hours, or calendar time. Third, oil analysis tells the truth — a few dollars per sample lets you safely extend intervals on healthy units and catch a failing one early, replacing guesswork with data specific to your trucks and your routes.