* Increased wear and tear: Higher sulfur content can lead to increased deposits in the engine and exhaust system, shortening its lifespan.
* Fuel injector damage: The higher sulfur content can damage fuel injectors.
* Emission system problems: The diesel particulate filter (DPF) and other emission control components are designed for ULSD and could be damaged or clogged by farm diesel. This can lead to costly repairs or replacements.
* Voiding the warranty: Using fuel outside of manufacturer specifications can void your warranty.
In short, while it might work in a pinch, consistently using farm diesel in a 6.4 Power Stroke is strongly discouraged. Stick to ULSD for optimal performance and engine longevity.