Preventative Maintenance Schedule for Class 3–8 Trucks

Week 9 · PM intervals · Class 3–8

Every OEM has its own maintenance schedule, and every fleet has its own reality. Trucks that live in stop-and-go city routes or dirty job sites need different care than highway-only tractors.

This guide isn’t meant to replace OEM recommendations — it’s a practical starting point for building a PM plan for Class 3–8 trucks in real-world service.

Light/medium duty (Class 3–5) – gas & diesel

For service trucks and smaller units:

• PM-A (basic): Oil & filter, safety check – every 5,000–7,500 miles for gas, 5,000–10,000 miles for diesel depending on use.
• PM-B: PM-A plus fuel filters (diesel) and more detailed inspection – every 15,000–20,000 miles.
• Annual: Coolant, belts/hoses inspection, brake inspection, and full chassis review.

Units that idle a lot or do short trips may need shorter intervals, even if the mileage isn’t high.

Medium/heavy duty (Class 6–8)

For box trucks, day cabs, and road tractors:

• PM-A: Grease and safety check — often every 7,500–10,000 miles.
• PM-B: PM-A plus oil & filters — typically 15,000–20,000 miles, adjusted for duty cycle and fuel type.
• PM-C: PM-B plus fuel filters, deeper inspections, and more detailed wheel-end checks.
• PM-D (annual deep PM): All of the above plus aftertreatment checks, air dryer service, DEF and air filters, and FMCSA-style inspection.

Fleets that run heavy loads, dirty environments, or a lot of stop-and-go traffic should lean toward the shorter end of these ranges.

Adjusting for your routes and conditions

Your PM schedule should reflect:

• How many hours per day your trucks run.
• How much idling they do in winter or at job sites.
• Whether they spend time off-road, in gravel, or dusty areas.

Two fleets with the same truck model can have very different ideal PM intervals based on this.

Using your PM tracker to stay on top of it

Once you’ve decided on sensible PM intervals:

• Enter them into your fleet PM tracker.
• Schedule on-site PM days when multiple units are due.
• Review intervals every 6–12 months based on failures and inspection findings.

Need help tailoring a PM plan to your fleet?

We’ve seen what works — and what fails — across Class 3–8 units in Central Indiana. We can help you build a simple PM schedule, then support it with on-site service and inspection days.