Diesel in the US has a red dye added if it's for agricultural use. "Detection of red-dyed fuel in the fuel system of an on-road vehicle will incur substantial

Diesel in the US has a red dye added if it's for agricultural use. "Detection of red-dyed fuel in the fuel system of an on-road vehicle will incur substantial penalties." Presumably you have to piss off a cop in your diesel-powered vehicle enough for them to test your tank. https://en.wikipedia.org/wiki/Fuel_dyes https://en.wikipedia.org/wiki/Fuel_dyes