Hydrocracking – a severe, high temperature, high pressure refinery process that converts heavy black oil into gasoline and diesel fuel by cracking or breaking up larger molecules, in the presence of hydrogen and a catalyst.
Hydrotreating – a refinery process that reacts a fraction of crude oil with hydrogen at high temperature and pressure, in the presence of a catalyst, to improve colour and odour, and reduce sulphur content.
Low sulphur diesel fuel – fuel that contains less than 500 parts per million (0.05 wt per cent) sulphur, required for on-road applications, and may be used off-road.
Lubricity – The property of diesel fuel that lubricates moving parts in fuel pumps and fuel injectors to minimize wear.
Off-road diesel fuel – refers to diesel fuel that is used for off-road purposes (i.e., mining, farming, marine, etc.). Off-road diesel fuel is frequently dyed red or "marked" to show that it is exempt from provincial road taxes.
Regular sulphur diesel fuel – fuel that contains less than 5,000 parts per million (0.5 wt per cent) sulphur, may not be used on-road, and is usually used in off-road applications such as farming, forestry and marine.