Two fuels, two names, one common mistake. Here is what actually separates them.
| 28 second kerosene | 35 second gas oil | |
|---|---|---|
| Also called | Standard grade burning oil, premium kerosene, heating oil | Red diesel, tractor diesel, rebated fuel |
| Colour | Clear to pale straw | Dyed red with a fiscal marker |
| Typical use | Domestic and light commercial boilers, some cookers | Agricultural plant, static engines, some commercial burners |
| Viscosity | Lighter, flows and atomises at low temperature | Heavier, more energy per litre, waxes in cold |
| Duty treatment | Nil rate for heating use | Rebated rate, restricted to qualifying uses |
| Goes in a domestic kerosene boiler | Yes | No |
DESNZ Quarterly Energy Prices / QEP 4.1.1 standard grade burning oil / published 27 August 2026 / checked 23 September 2026 / lag 27 daysone to four weeks oldtier A
Typical price for a delivery of up to 1,000 litres, VAT at 5% included. Observed on the Monday nearest the 15th. The official series covers standard grade burning oil, which is the domestic grade in the left hand column.
Why the price gap is not what you would guess
Gas oil carries more energy per litre than kerosene, so on energy content alone it should be the dearer fuel. The reason it is not always dearer at the pump is duty. Heating kerosene is charged at a nil rate. Gas oil carries the rebated rate, which is low but not zero. That difference shifts the ranking and it moves whenever rates change.
We do not publish a live gas oil retail figure here, because the domestic buyer on this site does not have a legitimate use for it. If you are running agricultural plant, the fuel duty guidance is the document to read, and the restrictions on qualifying use have tightened rather than relaxed.
What happens if the wrong grade goes in
- A kerosene burner fed gas oil will typically smoke, soot the heat exchanger and lock out. It is a service call and a clean, not a catastrophe, but it is not free.
- The red dye is a fiscal marker. It stays in the system, and it is detectable long after the fuel has burned.
- Using rebated fuel outside its qualifying use is a duty matter, not a quality matter. That is the reason to care rather than the boiler performance.
- If a delivery went wrong, ring the supplier before you fire the boiler. Draining a tank is cheaper than cleaning a heat exchanger.
The American reader
None of this maps onto the United States. American home heating oil is No. 2 distillate, which is closer to the UK gas oil end of the range than to kerosene. A price quoted in dollars per gallon and a price quoted in pence per litre are not describing the same fuel, which is why this site keeps the two desks apart.
Primary sources for this page
- ASTM D3699 standard specification for kerosineThe specification behind the grade names. Paywalled, cited for the definition rather than quoted.
- HMRC Excise Notice 192, registered dealers in controlled oilThe RDCO scheme. It is a statutory approval to deal in rebated oil, it is not published as a searchable consumer register, and it is not a quality or price guarantee.
- HMRC fuel duty ratesKerosene used for heating is charged at a nil rate of duty. Gas oil carries the rebated rate.
- DESNZ Quarterly Energy Prices, table 4.1.1Monthly typical retail price of standard grade burning oil, the fuel sold to UK households as kerosene. Priced on the Monday nearest the 15th of the month, for deliveries of up to 1,000 litres, VAT at 5% included. This is the only official UK-wide domestic heating oil price series.