MODULE GP-SPEED & VIBRATORY 2105940 - Caterpillar

Caterpillar-Built Truck EnginesDuring the colder, winter months truck owners often question a decrease in fuel efficiency. Reports have shown some owners do not understand the reasons for a decrease in miles per gallon (mpg). Reports have shown a decrease by as much as 1 mpg in some cases.
Many truckers use a mixture of Number 1 and Number 2 diesel fuel during cold weather. This mixture is used to prevent fuel waxing. The Number 1 diesel fuel is lighter; it has less wax than the Number 2 fuel. With a mixture of Number 1 and Number 2 diesel fuel, more fuel must be burned to get the same horsepower. Tests have shown that a 50-50 mix of Number 1 and Number 2 can give a reduction of .1 mpg.
It is also important to note that Number 1 diesel fuel costs more than Number 2.
Increased rolling resistance of cold tires is another factor that causes a decrease in fuel efficiency. It is estimated that a tire at -1°C (30°F) will give a reduction of 1 mpg in the first half hour of operation, when compared to operation at 21° to 29°C (70° to 85°F). In the second half hour of operation, the loss will be approximately .7 mpg. As tires warm up, the loss stabilizes at about .4 mpg.
A decrease in engine efficiency can result when the engine runs at a cooler temperature. Engine oil temperatures are lower, resulting in thicker oil and more drag (friction). This is especially true when the engine is equipped with outboard-mounted oil filters.
Rain, snow or ice splashed against the engine, contribute to a cooler engine operation temperature. Traction is also decreased by precipitation. These factors combined can cause a further decrease of .2 to .3 mpg when the temperature is -1°C (30°F) instead of 21° to 29°C (70° to 85°F).
Additionally, transmission and axle lubricants stiffen, increasing drag. Cold ambient air is more dense, so the aero-dynamic drag increases. Winter winds are usually more severe and more frequent. A head wind or side wind will decrease fuel efficiency. Again, these conditions combined can reduce fuel efficiency by as much as .4 mpg.
Fuel efficiency is further reduced by a change in driving habits during the winter months. Idling time is increased. A driver will be more cautious on icy or wet roads. He will decelerate to a slower speed so additional acceleration is needed to return to cruising speed.
All these factors combined can cause a significant decrease in mpg during the winter months. To minimize the effects of the cold weather, you should make sure your water temperature regulators are working properly. On most engines, Caterpillar recommends replacement of the temperature regulator at 100,000 miles. See the Operation and Maintenance Guide for more specific information. If you have an on-off fan, make sure it is in good operating condition. Shutters can be installed to maintain a higher engine temperature. Also, keep idling time to a minimum. All these measures will help fight the effects of the