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Trusted by over 500,000 customers for 20+ years
Order online or call
01480 775454
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Trusted by over 500,000 customers for 20+ years
Written by
Siobhan Brewer
on 09 Jan 2024
and updated on
03 Feb 2026
Categorised in
Tips and Advice
Heating oil additives commonly refer to a liquid that is added in small quantities to the oil in your tank. These are normally added either just before, or just after a delivery of fuel to ensure best results. Often, only one bottle is needed for an entire tank.
The ingredients used in additives vary from brand to brand but normally include antioxidants, detergents and other fuel stabilisers. Often, additive manufacturers will include a sweet fragrance in the mixture to help mask the regular (not-so-nice) smell of kerosene.
It’s all clean, clean, clean with additives! When you have treated your tank with an additive, the ingredients work together to ensure your system runs clean.
Deposits build up on the boiler nozzle over time, meaning more fuels needs to be burnt to achieve the same heating levels. Sludge and other deposits can also build up in fuel lines and tanks as the kerosene degrades over time. Additives help to remove all of this.
By doing this, it ensures a cleaner fuel moves through your system at a better rate, burning in a cleaner way, and using less fuel than before. This means your system runs more efficiently, uses less oil and ultimately costs you less to keep your home warm. But the benefits don’t stop at the day to day running.
By using heating oil additives, there is a reduced risk of failing parts or boiler breakdowns. If you’ve experienced a boiler breakdown before, you will know it’s not only inconvenient to be without heating, but also can be costly for a boiler engineer callout. Heating oil additives are working for you beyond your oil tank!
Most homeowners view heating oil as a standard commodity, but its quality can degrade during storage. Heating oil additives help stabilise fuel and prevent sludge accumulation and, for homeowners with metal oil tanks, reduce the risk of internal corrosion.
By improving the combustion process, these chemical treatments ensure your boiler runs at peak efficiency, reducing fuel consumption and preventing costly emergency breakdowns.
Whether you are looking to extend the life of an aging tank or maximise the heat output of a modern condensing boiler, understanding the chemistry of your fuel is the first step toward a more reliable home heating system.
For a household using around 1,000 litres of heating oil per year, the table estimates fuel savings of £58 at an average oil price of 58p per litre - more than enough to cover the £25.99 additive cost - resulting in a net benefit of about £32.
Fuel savings from heating oil additives are typically modest in well-maintained systems. However, where fuel quality is poor or sludge and deposits are present, additives can deliver greater efficiency improvements. In such cases, efficiency gains of around 10% may be achievable, though results can vary and are not guaranteed. These improvements can help increase savings beyond those shown and reduce the risk of boiler breakdowns.
| Usage (litres) | Saving* | Additive Cost** | Net Benefit |
|---|---|---|---|
| 1,000 | £58.00 | £25.99 | £32.01 |
| 1,500 | £87.00 | £38.99 | £48.02 |
| 2,000 | £116.00 | £51.98 | £64.02 |
| 2,500 | £145.00 | £64.98 | £80.03 |
| 3,000 | £174.00 | £77.97 | £96.03 |
* Savings based on an average oil price of 58p per litre.
** One bottle of additive treats 1,000 litres.
There are a couple of options for additives with us, BoilerMax and ElimiNOX Eco. They both provide similar efficiency boosting properties and should save you money in the long run, not to mention the additional benefit of reduced boiler breakdown risk. The key differences between the BoilerMax and ElimiNOX additives are:
BoilerMax is for standard heating systems, helping reduce sludge, deposits, and corrosion. BoilerMax Fresh offers the same protection with a cherry fragrance to help mask the smell of kerosene, ideal for boilers. For AGA or Rayburn cookers, use CookerMax, which is specifically formulated for oil-fired cookers.
ElimiNOX Eco is the more environmentally conscious option, made from biodegradable ingredients. It removes free water from fuel to help prevent microbial growth and reduce the risk of internal tank corrosion and is suitable for use with AGAs and Rayburns.
The easiest way to buy your additive is when ordering your heating oil. Once you choose your delivery option, we’ll offer you the option of adding BoilerMax to your order. This means your additive will be with you ready to use when you top up your tank. By adding with your delivery, you’ll maximise your efficiency gains on a full tank.
You can also buy additives separately in our Shop. By purchasing through Shop, you’ll be able to get multi-buy savings, getting 3 bottles for a much lower cost per unit! This is where you can choose ElimiNOX or the BoilerMax scented version for a sweeter smell when your boiler kicks into life.
Price Charts
Buy 3 for just £22.00 per bottle - each bottle treats 1000L of heating oil.
