Fuel dyeing is a common requirement in many countries to enable authorities to easily determine a low-taxed fuel from other variants of high-taxed fuel. Typically, fuel that is dyed is known as low-taxed (or sometimes untaxed) fuel while clear fuel is the one paid with high tax. One popular example of a dyed fuel is called red diesel, as it is called in the United Kingdom, but it is also known as medium diesel, gas oil, tractor diesel, heating oil or generator fuel in other countries.
This type of cheap fuel, red diesel, is particularly used in vehicles that rarely passes through main highways such as vehicles used for agricultural and winter road assistance purposes. Also, red diesel is used as fuel to operate electrical generators and construction machineries such as tower cranes, land drillers and excavators, and skip loaders. Aside from land vehicles and machineries, red diesel can also be used for water vehicles such as motor boats.
Due to technological and environmental requirement, red diesel is created from mixing relatively less toxic solvent dyes to fuel instead of powdered dyes. This is for the reason that it has been discovered that it is more efficient way to obtain concentrated fuel mixture by mixing solvent dyes with fuel that their solid counterpart.