ROD AS 2478493 - Caterpillar

Determine if water is present in the fuel. Check the water separator (if equipped). Drain the water separator if water is present.
Remove a sample of fuel from the fuel tank. Visually inspect the fuel for contaminants. The color of the fuel does not indicate the quality of the fuel. In cold ambient temperatures, the fuel may appear cloudy. The cloudy appearance indicates that the fuel may not be suitable for cold operating conditions. When the fuel becomes cloudy, the natural waxes in the fuel will start to solidify. When the waxes solidify, the fuel filters will become plugged. To prevent the fuel filters from plugging, use one of the following solutions:
Fuel heaters
Blending fuel with additives
Fuel with a low cloud point
Check the API of the fuel with a 5P-2712 Thermometer/Hydrometer for low-power complaints. The acceptable range for the API gravity at 15 °C (59 °F) is 30 to 45. Fuel that has a higher API gravity will supply more power.
If the quality of the fuel is still suspected as a possible cause of poor engine performance, disconnect the fuel inlet line. Temporarily operate the engine with fuel that is known to be good. This procedure will determine if the poor engine performance is caused by fuel quality. The cetane number, air in the fuel, and other characteristics can affect engine performance.