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HMRC internal manual

Oils Technical Manual

Imports of Mineral Oil: Directions for particular goods: Fuel substitutes and additives

All imported substitutes for road fuels and any additives for road fuels are to be charged with UK excise duty at the same rate as the oil for which they substitute for (or are added to).

Additives should be charged with UK excise duty on 100% of their volume and not simply on the percentage of them which contains hydrocarbon oil.

Imported lubricating oils outside the excise definition of gas oil should not be charged with UK excise duty (Tax Type Code 570).