An unexpected breakdown on the interstate doesn't just cost thousands in heavy-duty towing and dealership labor rates—it results in missed delivery windows, broker claims, and lost revenue days. A rigorous Preventive Maintenance (PM) program based on structured service intervals is the cornerstone of reliable fleet operations.

1. The 3 Tiers of Class 8 Maintenance

• PM-A (Weekly / Daily Pre-Trip): Checking oil and coolant levels, tire inflation (100–110 PSI cold), wheel seal leaks, brake shoe thickness (>1/4"), air brake governor cutoff/cut-in pressures, and fifth-wheel locking mechanisms.
• PM-B (Every 15,000 – 25,000 Miles): Complete engine oil and filter change, primary and secondary fuel filter replacements, coolant freeze-point testing, chassis grease lube (kingpins, universal joints, slack adjusters), and fluid sample oil analysis.
• PM-C (Annual / Every 100,000 Miles): Transmission and differential gear oil flush, cooling system flush, air dryer cartridge replacement, valve lash adjustment (overhead tune-up), and Diesel Particulate Filter (DPF) ash cleaning and SCR emissions inspection.