What Counts as Severe Duty Service for a Car?

Short trips, trailers, and dust can take a big toll on your vehicle.

Ronan Glon | 

May 13, 2024 | 3 min read

GMC

Think of severe duty driving conditions as dog years for cars: Every mile driven puts the equivalent of many more miles of wear on the vehicle's mechanical parts. While some vehicles are designed for very tough conditions, they will need more frequent maintenance to withstand severe-duty driving.

Severe Duty Explained

Broadly speaking, automakers define severe duty as operating conditions that regularly put an unusually high amount of strain on a vehicle. GMC cites driving primarily in dense, low-speed urban traffic in hot weather, routinely driving through hilly or mountainous terrain, and regularly towing a trailer as examples of severe duty. Vehicles often driven at high speeds or used for commercial purposes, such as patrol cars, taxis, and delivery trucks, also experience severe duty conditions.

Vehicles primarily used for short trips or in dusty conditions are also subjected to severe conditions.

Oil flows better as it gets hotter and moves freely through the engine. On a short trip, however, the oil may not get hot enough to properly lubricate the engine, which can increase wear on crucial parts. Moisture that can build up in the oil doesn't fully evaporate during short trips, further reducing the oil's ability to lubricate components such as the pistons and crankshaft.

Dust and sand can clog the air filter, affecting the engine's performance. The filter's role is to prevent contaminants from entering the engine through the intake system, but it restricts airflow when it becomes dirty. This can cause the engine to overheat and damage internal parts.

Severe Conditions Can Affect a Car's Maintenance Schedule

Vehicles regularly driven in severe conditions require more frequent maintenance to avoid costly problems. The recommended service intervals vary from manufacturer to manufacturer. You can find these details for your vehicle in the owner's manual.

For example, GMC recommends changing the Sierra pickup truck's engine oil every 7,500 miles but warns that the oil life indicator can come on sooner if a truck is driven in severe conditions. GMC adds that the truck's spark plugs might need to be replaced more frequently and suggests changing the transfer case fluid every 25,000 miles instead of every 50,000 miles for pickups that operate in normal conditions.

Owners of Ram trucks regularly operated in severe dusty conditions are advised by the truck maker to inspect the evaporative system's fresh air filter and replace it if necessary.

The Dangers of Ignoring Severe Duty Maintenance

Not following a severe duty-specific maintenance schedule can cause major mechanical problems that can leave you stranded, cost you a substantial amount of money to fix, or both.

Whether it's due to a clogged air filter or a cooling system-related problem, overheating can cause the head gasket to blow or warp the cylinder head. Dirty oil can reduce your engine's lifespan and, in extreme cases, cause irreparable damage, as contaminants can notably leave scratches on the pistons and cylinders.

Ronan Glon

Ronan Glon is an American journalist and automotive historian based in France. He enjoys working on old cars and spending time outdoors seeking out his next project car.