Which heating oil do I need: standard, premium or AGA oil?

The three oils Fueltool compares

Kerosene or gas oil?

Which? describes kerosene, also called 28-second oil or simply heating oil, as the most common type used in UK homes. Gas oil, also called 35-second oil or red diesel, is usually used in older boilers, in agriculture or commercially. Both are made to the British Standard BS 2869: kerosene as Class C2 and gas oil as Class D.

Kerosene is the lighter of the two. Which? says it is unlikely to wax up in cold weather until around minus 39°C, though this can vary between suppliers; see does heating oil freeze.

A burner is set up for one fuel. OFTEC's technical guidance notes that burner nozzles are calibrated for a specific fuel such as Class C2 kerosene or Class D gas oil, and its tests found nozzles calibrated for those fuels running up to 10% out at their calibrated pressures when used with HVO instead. Never switch fuels on your own: changing a burner from one fuel to another is a job for an OFTEC-registered technician.

Premium and AGA oil: do you need them?

Premium Kerosene is for kerosene boilers. It is the same fuel with a boiler additive, not a heavier grade, and it is not suitable for AGAs. Whether the additive is worth having for your boiler is a question for its manual or your service engineer.

AGA / Range Cooker Oil is kerosene with an additive made for AGA-type cookers. If one tank feeds both a boiler and an AGA, don't choose Premium Kerosene; check the cooker's manual or ask your engineer whether standard Heating Oil or AGA / Range Cooker Oil is the right choice.

The tax rules on heating fuels

HMRC's rules say rebated kerosene must be marked and can only be used to generate heat for premises, and it is illegal to use it in a vehicle without an HMRC permit. Red diesel, which is rebated gas oil, can be used in appliances that heat premises not used for commercial purposes, and premises mainly used as someone's home count as non-commercial. See who can use red diesel for the wider rules.

How to check what you have

• Look in the boiler or cooker manual, or on the appliance's data label.
• Check your last delivery note or invoice for the product that was delivered.
• If the boiler or tank isn't clearly labelled, Which? suggests asking the previous owner what they used.
• If you still aren't sure, ask an OFTEC-registered technician. OFTEC's online search finds registered technicians for oil boiler servicing and repairs.
• If you're thinking about a lower-carbon fuel, a full switch to HVO needs changes to the appliance; see HVO in oil boilers.

Once you know your oil, compare prices for your postcode.