Red diesel

Gas oil is a commonly used fuel in construction, agricultural and marine industries throughout the UK and the rest of the world. It is also known by a number of other names, such as red diesel, cherry diesel, 35 second oil and tractor diesel.

It is commonly referred to as red diesel because of its principal differentiating characteristic from other petroleum derivatives: a red dye that is dissolved in the liquid. In the UK, this is done to distinguish it from road diesels, which are subject to higher taxation. The use of red diesel is strictly limited to vehicles and devices which rarely operate on the roads, such as tractors, cranes and generators, as well as boats.

However, because gas oil is subject to lower taxes, some motorists have been known to use red diesel to power cars and vans in an effort to save costs. As such, the police carry out regular roadside checks to establish whether people have filled their tank illegally by checking for signs of colouration.

In its composition, red diesel is similar to regular on-road diesel and is distilled from crude oil via a process of fractional distillation. The main difference is that gas oil is distilled at a lower temperature and as such has a molecular structure consisting of longer carbon chains than is found in regular diesel. As such, it has a higher boiling point and burns less efficiently than road diesel.

Many industries rely on red diesel to fuel a range of vehicles, as well as for industrial heating processes. In the UK, there is a robust supply and delivery infrastructure serving the needs of construction and agricultural sectors, as well as gas oil bunkers which can be found at ports around the country where marine industries can purchase the fuel.

Along with all other classes of petroleum derivatives, red diesel is subject to regulation by the British Standards Institute, which sets out stringent tests for quality and designates the specific uses for red diesel and other types of fuel. The standard was last updated in 2006, when a number of changes were made to rules governing gas oil and other distillates and residual fuels.