Essential maintenance plan for a used 2018 diesel truck towing a travel trailer.

[MichaelKM]

I recently bought a used diesel truck, a 2018 model with about 80,000 miles, to use for towing my travel trailer, and I want to make sure I'm proactive about its maintenance to avoid any costly repairs down the line. I'm familiar with basic gasoline engine care, but I know diesels have specific needs like dealing with the diesel exhaust fluid system and fuel filter changes. For experienced diesel truck owners, what does your essential maintenance schedule look like beyond oil changes, and what are the most common failure points I should be inspecting regularly? How critical is it to use fuel additives, and what signs should I watch for that might indicate issues with the turbocharger or emission control systems before they become major problems?

[Aaron49]

You're on the right track. For a 2018 diesel used to tow a trailer, a simple, practical maintenance cadence helps a lot beyond oil changes:
- Oil & filter: roughly every 7,500–10,000 miles with a high-quality diesel oil; follow the vehicle’s manual for exact spec and intervals.
- Primary fuel filter: inspect/replace per OEM schedule, often around 15,000–30,000 miles depending on usage and fuel quality; tow duty may want the earlier side.
- Air filter: every 15,000–30,000 miles; more often in dusty conditions.
- DEF system: keep the reservoir topped up, use the correct formulation, and watch for any DEF heater or sensor warnings.
- DPF and exhaust: monitor for regeneration frequency; if you’re seeing frequent forced regenerations or the dash warning, investigate exhaust leaks, sensor faults, or a plugged DPF.
- Cooling system: check coolant level and condition; inspect hoses and the radiator; consider a coolant flush per manufacturer schedule (often around 100k miles).
- Drivetrain and transmission cooling: ensure the transmission cooler lines are intact and fluid is at the right level; tow duty can shorten fluid life.
- Drivetrain fluids: differential and transfer case fluids checked and replaced per manual; inspect seals for leaks.
- Belts, hoses, battery: check belts for wear, inspect hoses for cracking, test battery health, especially in cold climates.
- Brakes and tires: towing wears tires quicker and can affect braking; rotate and inspect for wear patterns.
- Regular inspection habit: look for oil or fuel leaks, soot buildup, or corroded connectors—catching those early saves big money.