General Motors Corporation recommends that owners of 1985 and subsequent Model Year diesel engine vehicles use Number 2-D diesel fuel above 20°F (-7°C) ambient temperature. If the ambient temperature is expected to be below 20°F, Number 1-D diesel fuel is recommended. (Figure 4-3). A “winterized” blend of Number 2-D and Number 1-D fuels may be used if Number 1-D is unavailable.
General Motors will not recommend the use of Number 2-D diesel fuel below 20°F unless it is “winterized” . Temperatures below 20°F will cause the “ non-winterized” fuel to thicken which may keep the engine from running.
The colder temperatures will cause number 2 diesel fuel to thicken or cause a wax build-up. This wax buildup could plug the fuel filter and keep the engine from running. However, if the car is towed in and sets in a warm garage, the wax will disappear. On no start complaints in cold weather, ask which grade of diesel fuel is in the tank.
For the best fuel economy, use Number 2-D fuel whenever temperatures will permit.
