Changing to a lighter grade engine oil also makes starting easier under these conditions. Refer to Engine oil specifications.   See   Capacities and Specifications - 6.8L. 

Diesel fuel is adjusted seasonally for cold temperatures. Diesel fuel which has not been properly formulated for the ambient conditions may gel which can clog the fuel filters. One indication that the fuel filter(s) may be clogged is if the engine starts, stalls after a short time, and then does not restart. If you have been using biodiesel, you may need to use a fuel with lower biodiesel content, try another brand, or discontinue using biodiesel. Do not use alcohol based additives to correct fuel gelling. This may result in damage to the fuel injectors and system. Use the proper anti-gel and performance improvement product.   See   Capacities and Specifications - 6.8L. 

Your vehicle is equipped with a fuel and water separator that recirculates fuel from the engine to help prevent fuel filter clogging. To avoid engine fuel starvation during cold weather operation of 32 °F (0 °C) or below, we recommended that the fuel level in your tank should not drop below 1⁄4 full. This helps prevent air from entering the fuel system and stalling the engine.

Your vehicle is equipped with a selective catalyst reduction system that uses Diesel Exhaust Fluid (DEF) to operate properly. You need to replenish your vehicle’s DEF at certain intervals. When filling your vehicle’s DEF tank in cold weather, you must take special care to prevent damage to the tank.   See   Selective Catalytic Reductant System - Diesel. 

In cold weather below 32 °F (0 °C), the engine may slowly increase to a higher idle speed if left idling in park (P) or neutral (N).

If you operate your vehicle in a heavy snowstorm or blowing snow conditions, snow and ice can clog the engine air induction. If this occurs, the engine may experience a significant reduction in power output. At the earliest opportunity, clear all the snow or ice away from inside the air filter assembly. Remove the air cleaner cover and the pleated paper filter, leaving the foam filter in and remove any snow or ice. Make sure you install the foam filter correctly in place. Remove any debris, snow or ice on the foam filter by brushing the surface with soft brush. Once you have cleared all of the debris, reinstall the air filter and assembly.

Do not use water, solvents, or a hard brush for cleaning the foam filter.

The following information is a guideline only and is not to be the only source of possible solutions in resolving extreme cold temperature issues.

The use of the factory engine block heater assists in engine starting in extreme cold ambient temperatures.   See   Engine Block Heater. 

Your vehicle may have a factory option for a stationary elevated idle control through dash-mounted upfitter switches that allows the operator to elevate the idle rpm for extended idle periods, as well as aftermarket equipment such as PTO operation. You must configure this feature even if ordered from the factory. See your authorized dealer for required upfitting.

Vehicle operation in heavy snowfall or extreme rain conditions may feed excessive amounts of snow or water into the air intake system. This could plug the air filter with snow and may cause the engine to lose power and possibly shut down.

We recommend the following actions after operating your vehicle up to 199 mi (320 km) in snowfall or extreme rain: