Does heating oil freeze in cold weather?

Kerosene and gas oil behave differently

UK heating oils are made to British Standard BS 2869, which covers Class C2 kerosene and Class D gas oil among other fuels. Standard heating oil is kerosene, and all three oils Fueltool compares are kerosene-based. UKIFDA, the distributors' trade body, says UK winters are usually mild enough not to pose a risk of freezing in tanks: kerosene only really causes problems when temperatures plummet to around minus 39°C, when it can turn waxy and crystals disrupt the flow.

Gas oil (Class D), which some boilers burn instead, is more sensitive to cold: UKIFDA puts the point where problems could arise at around minus 12°C. If your boiler runs on gas oil, ask your supplier before winter what it advises for cold weather.

What usually goes wrong in a cold snap

• A frozen condensate pipe. Condensing boilers drain water through a plastic pipe, sometimes outside. If it freezes, the boiler shuts itself down. Pour warm, not boiling, water slowly along the outside section from the top down, then reset the boiler as its instructions say.
• Water in the fuel. Rain, snowmelt or condensation that gets into the tank sinks below the oil and can freeze, cutting the flow of fuel to the boiler. UKIFDA says water in the tank is far more likely to cause problems than the cold itself. OFTEC advises keeping all caps, lids and vents secure. See our guide to water in an oil tank.
• Frozen water pipes. OFTEC suggests lagging heating and water pipes, and running the heating at a lower, constant temperature in cold spells rather than in short bursts.
• Running out. Delivery rounds slow down in bad weather just as you burn more oil.

Never use a flame or heat gun on a fuel line or oil filter. If the boiler will not restart, call an OFTEC-registered technician rather than attempting repairs.

Protecting the tank and pipes

Make sure the tank is checked at the annual service, and check it yourself regularly for visible cracks, leaks or other damage, as UKIFDA advises. A condensate pipe that keeps freezing can be insulated or rerouted: Which? recommends a professional assessment, waterproof and UV-resistant insulation, and a wider pipe. For an oil boiler, use an OFTEC-registered technician for this work. Keep the area around the tank and the fill point clear and accessible, including of snow and ice, so the driver can reach it safely.

Order before the cold, not during it

UKIFDA says not to wait until the tank is nearly empty, because demand rises as temperatures fall and deliveries need time. Its 2026 winter advice is to keep at least 300 mm (12 inches) of oil in the tank, which it says helps reduce sediment problems, and at least 500 litres where you can as a buffer against delays. If someone in your household is 75 or over, ask a UKIFDA member distributor to register you for the free Cold Weather Priority Scheme, which lets participating distributors prioritise your deliveries in extreme cold or a fuel shortage.

Each price on Fueltool shows its delivery option and date, so you can see how quickly oil can reach you before the forecast turns. Our guide on when to reorder has more detail. When it is time, compare prices for your postcode.