C7 Industrial Engine Operation and Maintenance Manual – Fuel and the Effect from Cold Weather

The following fuels are the grades that are available for Cat engines:


  • No. 1 
  • No. 2 
  • Blend of No. 1 and No. 2 

No. 2 diesel fuel is the most commonly used fuel. Either No. 1 diesel fuel or a blend of No. 1 and No. 2 is best suited for cold-weather operation.

Quantities of No. 1 diesel fuel are limited. No. 1 diesel fuels are usually available during the months of the winter in the colder climates. During cold-weather operation, if No. 1 diesel fuel is not available, use No. 2 diesel fuel, if necessary.

There are three major differences between No. 1 and No. 2 diesel fuel. No. 1 diesel fuel has the following properties:


  • Lower cloud point 
  • Lower pour point 
  • Lower rating of kJ (BTU) per unit volume of fuel 

When No. 1 diesel fuel is used, a decrease in power and in fuel efficiency may be noticed. Other operating effects should not be experienced.

The cloud point is the temperature when a cloud of wax crystals begins to form in the fuel. These crystals can cause the fuel filters to plug. The pour point is the temperature when diesel fuel will thicken. The diesel fuel becomes more resistant to flow through fuel pumps and through fuel lines.

Be aware of these values when diesel fuel is purchased. Anticipate the average ambient temperature of the area. Engines that are fueled in one climate may not operate well if the engines are moved to another climate. Problems can result due to changes in temperature.

Before troubleshooting for low power or for poor performance in the winter, check the type of fuel that is being used.

When No. 2 diesel fuel is used the following components provide a means of minimizing problems in cold weather:


  • Starting aids 
  • Engine oil pan heaters 
  • Engine coolant heaters 
  • Fuel heaters 
  • Fuel line insulation 

For more information on cold-weather operation, see Special Publication, SEBU5898, “Cold Weather Recommendations”.


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