"Heating oil" in the UK usually means one of two fuels. Ordering the wrong one can cause poor combustion, smoke and boiler faults, so it is worth knowing which you need.
Kerosene (28-second oil)
Kerosene is a light, clear fuel and is used by the vast majority of domestic oil boilers and range cookers in Great Britain and Northern Ireland. It burns cleanly, flows well in cold weather and is the fuel our headline prices refer to. The name "28-second" comes from an old viscosity test measuring how long a set volume takes to flow through a standard opening.
Gas oil (35-second oil)
Gas oil is heavier and is the same base fuel as red diesel. It is mainly used by farms, commercial premises and some older or larger boilers. Because it carries a rebated rate of fuel duty, gas oil is normally around 10–12p per litre more expensive than kerosene after tax.
Side-by-side
| Kerosene | Gas oil | |
|---|---|---|
| Typical users | Homes, range cookers | Farms, businesses, older boilers |
| Fuel duty | None for heating | Rebated rate |
| Cold-weather performance | Very good | Can thicken in hard frost |
| Colour | Clear / pale yellow | Red (dyed) |
How to check which fuel you use
- Look at the boiler data plate or the manual — it will state the fuel type.
- Check a previous delivery note or invoice.
- Ask your OFTEC-registered heating engineer at your next service.
Never switch fuels without a technician adjusting or converting the burner. You can compare current estimates for both fuels on our homepage price table.