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HMRC internal manual

Oils Technical Manual

Introduction and overview of oils activity: types of oil products and their use: types of fuel products

Mineral Oils

Crude oil is turned into a range of oil products by fractional distillation and by other conversion processes, including thermal and catalytic cracking, reforming and alkylation.

The crude is heated to about 350ºC and pumped into the bottom of the distillation column, the vaporised oil rises up the column, and as it cools its various components or fractions condense back into liquid. Those fractions with the lowest boiling points collect closest to the top of the column, whilst those with the highest collect at the bottom. Crude oil also contains a mixture of gases which do not condense and which are taken off as gas at the top.

The main fractions from fractional distillation are:

  • Petroleum gas - especially butane and propane
  • Gasoline (petrol)
  • Naphtha - used to manufacture chemicals and plastics, but also as a gasoline component
  • Kerosene (paraffin)
  • Gas oil -used in diesel engines
  • Lubricating oils
  • Heavy Fuel oils
  • Residues - used for making bitumen and some fuel oils.

The oil products which are produced as a result of distillation and other processes have a range of different qualities and properties, including their boiling point, flash point, viscosity and chemical composition. These differences make the oil products produced, suited for a variety of uses, but this also allows those with similar properties to be used as a substitute for each other. Alternatively, oil products may be mixed or blended together in order to produce a ‘new’ product with the required properties or qualities.


In addition to those ‘mineral’ oils produced from crude oil, increasingly ‘biofuels’ such as biodiesel and bioethanol are being produced from biomass, as alternatives to hydrocarbon oils. Biofuels may be used in place of conventional oils, or combined with these to produce blends such as bioblend (biodiesel and diesel) and bioethanol blend (bioethanol and gasoline).

For further information on Biofuels and other Fuel Substitutes see the guidance contained in HCOBIG ‘Biofuels Assurance’.