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1 October 2020

What is heating oil?

We talk you through the basics of heating oil, including the different types available, what they're used for and how to choose the right type of heating oil for your home.
Family warm at home in bed 451062
SI
Sarah Ingrams

Around 1.1m households in the UK are not connected to the national gas grid, and instead rely on heating oil to heat their homes. 

The key difference between gas from the grid and heating oil (as well as LPG) is that heating oil is delivered by road and stored in a tank.

If your home has an oil boiler, it runs on heating oil. Keep reading to find out what you need to know.

You can use our research to discover the most reliable oil boilers, based on ratings from owners and heating engineers.

What type of home heating oil do I need?

There are two types of oil used for domestic heating:

  • Gas heating oil – also known as 35-second oil or red diesel. This is a heavier oil generally used in older boilers, in agriculture or commercially.
  • Kerosene heating oil – also known as 28-second or heating oil. This is a lighter and cleaner fuel, and the most common type used in homes in the UK.

If you've just moved into a property, the type of oil you will need is determined by the type of heating system already installed. If your boiler or tank isn't labelled clearly, ask the previous owner what type they used. 

If they can't help, a technician registered with Oftec (the oil-fired industry trade association) should be able to tell you.

If you're able to choose which type to use, kerosene is the more efficient fuel. In cold weather it's unlikely to ‘wax up’ (form crystals that stop it from flowing as easily) until it reaches around -39°C (although check with the supplier, as this can vary). 

For more information on how to prevent waxing up, take a look at our tips on maintaining and fixing heating oil problems. 

Should I buy premium kerosene heating oil?

You can buy a premium type of kerosene that contains additives – this makes it burn more cleanly, and therefore more efficiently. Premium kerosene usually costs around £20 to £30 more than standard kerosene (based on 500 litres). You can also buy additives yourself, which cost around £15 for a bottle that will treat 1,000 litres of heating oil. 

For certain appliances, such as an Aga, you are required to use additives. You should be able to find this out from the manufacturer.

How much does heating oil cost?

The price of heating oil can fluctuate quite dramatically over time. Having hovered between 30 and 35p per litre in 2016, it shot up to nearly 55p per litre in late 2018, staying at around 50p per litre until January 2020. 

However, its price dropped dramatically in spring and summer 2020, to a five-year low of just 25p per litre in July 2020. 

Price fluctuations can be down to a number of factors, including global production increasing or decreasing, extreme weather, or political unrest. Prices can also vary greatly depending on where you live in the UK, the time of year you buy, and the amount you buy.

There are several ways to get a cheaper deal – take a look at our detailed graph on price fluctuations, and find out more about how to get the best best heating oil prices