Fuel System Description: Fuels

Bio-Diesel Fuel 

It is acceptable to use diesel fuel containing up to 20 percent biodiesel (B20), but the final blended fuel must meet the same specification, ASTM D 975 (Grades No. 2-D or No. 1-D S15 commonly known as Ultra Low Sulfur diesel), as the other fuels used in your vehicle, and the biodiesel used for making this fuel must meet the latest version of ASTM specification D 6751. Biodiesel is produced from vegetable oils or animal fat that have been chemically modified to reduce the possibility of damage to the fuel system and engine. Higher concentration (i.e. greater than B20) biodiesel-containing fuels or the use of unmodified bio-oils blended into diesel fuel at any concentration is not recommended and could damage the fuel system and engine. Such damage would not be covered by your warranty. If there are questions about the biodiesel-containing fuels you are using, contact your fuel supplier.

Because of the cleansing properties of biodiesel, switching from straight diesel to a biodiesel blend can prematurely restrict the fuel filter with normal deposits in the fuel system. A fuel filter replacement might be required sooner than the recommended interval.

Diesel Fuel 

For best results use Number 2-D diesel fuel year-round, above and below freezing conditions, as oil companies blend Number 2-D fuel to address climate differences. Number 1-D diesel fuel may be used in very cold temperatures when the temperature stays below -18°C (0°F). However, the fuel will produce a power and fuel economy loss. The use of Number 1-D diesel fuel in warm or hot climates may result in stalling, poor starting when the engine is hot and may damage the fuel injection system.

Diesel fuel may foam when filling the tank. This can cause the automatic pump nozzle to shut OFF, even though the tank is not full. If this happens, just wait for the foaming to stop and then continue to fill the tank.

Diesel Fuel Containing Red Dye 

The Governments of the United States and Canada impose an excise tax on diesel fuel. However, certain fuel uses are tax-exempt or subject to a reduced rate. These uses include: heating, farming, off-road vehicles, use by state or local governments or non-profit educational organizations, and boats engaged in fishing or transportation.

• The red dye is added to identify tax-exempt diesel fuel to ensure it is not used for taxable purposes.
• The use of red diesel fuel will not cause any problems with the fuel or exhaust aftertreatment systems.

Very Cold Weather Operation 

If the vehicle is driven in very cold temperatures and cannot get a winterized Number 2-Diesel that has been adapted to cold weather, a Number 1 - Diesel may be supplemented. Only use Number 1 - Diesel when the temperature falls below -18°C (0°F), because the fuel economy is not as good as that of Number 2 - Diesel fuel. To prevent waxing or gelling of the diesel fuel, use 50% Number 1 - Diesel in the fuel tank and add a container of GM approved Diesel Fuel Treatment. The additive is a preventative and must be added when filling the tank and before any waxing or gelling occurs.

In cold weather, the fuel filter may become clogged (waxed). To unclog the filter, move the vehicle to a warm garage area and warm the filter to a temperature between 0 - 10°C (32 - 50°F). Replacing the filter is not necessary.