Here are some of the most critical maintenance procedures that need to be scheduled.
While checking and draining the water/fuel separator is normal maintenance for any type of engine in any season, it is particularly critical in cold-weather conditions and for vehicles running on biodiesel. Biodiesel usually contains more water than regular diesel, and thus requires more frequent fuel filter changes. Natural gas engines produce even more water vapor, and must be checked and drained daily.
A simple hydrometer check or test strip will tell you if the antifreeze in the radiator needs a supplemental additive or a complete change. The concentration of ethylene glycol and water will vary depending on temperatures where you operate. There are also significant differences depending on the chemical makeup of the antifreeze/coolant that you use. Check your Operation and Maintenance Manual for specific recommendations. At the same time, a visual inspection of the thermostat, seal, and hoses should be performed to make sure there are no cracks or leaks. Anyone operating diesel or natural gas engines in climates that stay below 11°F (-12°C) for extended time periods probably have coolant heaters and oil heaters that need to be checked.
While people put on heavier clothes in winter, engines need lighter-weight oil in their crankcase. Those running 15W-40 oil should consider switching to a 10W-30 or lighter-weight oil that meets OE specifications for diesel engines.