Winter weather and the harsh driving conditions that come with it can have a pronounced effect on any vehicle. Nevertheless, vehicle downtime can be minimized and performance and reliability can be maintained through winter preparation measures that should be part of every fleet’s maintenance operations.

The following is a roundup of guidelines from truck manufacturers for winterizing vehicles:

  • Tires: To maximize traction, make sure tire air pressures are correct. Cold weather reduces tire pressure, so check and adjust frequently. Also, check tire and tread condition. Worn tires can compromise a vehicle’s traction when it is wet and slippery. It is recommended that tread thickness be a minimum of 5/32-inch for winter driving.  If chains are used, it is important that they be the correct size for the tires and be properly installed.
  • Brakes: Inspect brake lining condition and check for leaking wheel seals. Ensure proper braking from each wheel as well as the operation of the anti-lock braking system. Properly functioning brakes can keep a vehicle in control and minimize skidding. For vehicles with air brake systems, service the air dryer. Be sure to drain all air tanks daily.
  •  Windshields, wipers, windshield washers, heaters and defrosters: These areas all need to be in good working order to allow clear vision at all times. Windshields should be checked for minor chips and pitting. As temperatures decrease and sheet metal contracts, stress on windshields can increase. Have small chips repaired to help avoid crack propagation and the need for a full windshield replacement. Windshield wiper blade conditions should be examined and replaced if necessary. Look for signs of wear, like cracking or discoloration, and check the quality of the wiper. Windshield washer fluid reservoirs also should be checked and filled regularly, and proper winter dilution levels should be used to avoid freezing. Heater and defroster operations should be tested, including the function/position of the directional vanes in the system to ensure effective defrosting.
  • Fuel system: As the seasons change, it is a good idea to check the diesel fuel grade as well as the cetane rating on the pump. The cetane number is a measure of the readiness of a fuel to auto-ignite when injected into a diesel engine. The higher the cetane number, the easier the vehicle will start in cold weather.

Diesel fuel is sensitive to temperature. All diesel fuel contains paraffin components, which are high in energy value and help improve fuel economy. When temperatures dip below 20 degrees Fahrenheit, the paraffin components begin turning into wax flakes. If temperatures are low enough, these flakes can obstruct fuel filters and stop fuel from reaching the engine, leaving the vehicle stranded and cold. To minimize chances of fuel waxing (gelling), maintain fuel filters and drain fuel water separators and fuel tanks of any accumulated water to prevent freezing. Service the fuel water separators and verify that they are working properly. Also verify operation of fuel heaters, if so equipped.

Onboard fuel tanks should be clear of water and sediment, and caps and connections should be tight.

It is advisable to refuel at the end of a day’s operation or before leaving a vehicle standing for an extended period of time, as moisture will condense in an empty fuel tank.

  • Engine oil: Be certain the proper oil grade is being used for cold weather because this will make starting easier. Colder temperatures require lower-grade oils for correct flow during starting. Higher temperatures, in turn, call for higher grades for proper lubrication.  The Society of Automotive Engineers (SAE) defines oil viscosity by grade. Basically, viscosity is determined by oil’s resistance to flow. Consult the vehicle’s owners manual for the recommended oil viscosity. In addition, all engine fluids should be at the proper levels.
  • Cooling system: Check all fan belts and coolant hoses for damage and replace if necessary. Make certain all hose clamps are tight. Also, check the condition of the radiator, radiator cap, fan, fan shroud and fan clutch to see that they are all in good working order. The protection level and quality of the coolant in the system should be verified. Winterizing the cooling system can be done by using a 50/50 mixture (48/52 for colder climates) of the vehicle manufacturer’s recommended coolant and water for freeze protection.
  • Batteries and charging systems: Check the batteries and charging systems for condition and proper operation. It is under the high starting load batteries face in cold weather that they typically fail.  The following measures should be taken: inspect and clean all battery cables and posts; clean, tighten and grease all terminals;  be sure batteries are securely mounted; and load test batteries to determine their condition and make sure they are fully charged, as freezing conditions drain a battery faster. A partially charged battery is subject to damage by freezing temperatures.
  • Exhaust systems: Inspect vehicle exhaust systems, particularly on gasoline engine models, to ensure they are free of leaks. Sitting in slow-moving traffic, creeping because of heavy snow or being parked with the engine running to maintain cab temperature can increase the risk of carbon monoxide entry into the cabin.  BI