Free heating oil tool · Updated 5 August 2026

Are Heating Oil Additives Worth It?

At a conservative 2% efficiency gain, a home using 1,200 litres a year saves about 24 litres, worth roughly £23.31 at today’s 92.5p per litre (5 August 2026). Against £30.00 of additive that is a loss of £6.69, so at honest inputs it usually does not pay for itself.

The numbers

Annual oil use (litres)

Oil price (pence per litre)

Defaults to today's UK average of 92.5p.

Cost per treatment

Treatments a year

Claimed efficiency gain2%

Default 2% is a conservative figure. Manufacturer claims are unverified.

Does it pay for itself?

Additive cost a year£30.00

Fuel saved a year£23.31

About 24 litres saved at 2%.

Net position a year

-£6.69

On these inputs this additive does not pay for itself. The fuel it might save is worth less than the additive costs.

Worked example: does an additive pay for itself?

Take a home using 1,200 litres of kerosene a year and dosing the tank 2 times at about £15.00 a treatment. That is £30.00 spent on additive over the year.

We apply a conservative 2% efficiency gain, which is deliberately cautious because independent verification of additive claims is thin. A 2% gain means the boiler needs about 24 fewer litres for the same heat. At today's UK average of 92.5p per litre (surveyed on 5 August 2026), that saved fuel is worth roughly £23.31 including 5% VAT.

So the household spends £30.00 to save £23.31, a loss of £6.69 over the year. To simply break even, the additive would need to deliver a genuine gain of about 2.6%. At honest, conservative inputs, a fuel additive usually does not pay for itself, and that is the answer this tool is built to give you straight.

Net position by claimed gain, 1,200 litres at 92.5p

Claimed gain	Litres saved	Fuel saved	Net vs £30 additive
1%	12 L	£12	-£18
2%	24 L	£23	-£7
3%	36 L	£35	+£5
5%	60 L	£58	+£28
8%	96 L	£93	+£63

Assumes 2 treatments a year at £15.00 each and today's price of 92.5p per litre including 5% VAT. The efficiency gain is unverified: the higher rows reflect manufacturer claims, not independent evidence.

How this is calculated

additive_cost = cost_per_treatment * treatments_per_year
              = £15.00 * 2 = £30.00

litres_saved  = annual_litres * claimed_gain
              = 1200 * 0.02 (conservative, unverified) = 24 L

fuel_saved    = litres_saved * ppl / 100 * (1 + vat_domestic)
              = 24 * 92.5 / 100 * (1 + 0.05) = £23.31

net_position  = fuel_saved - additive_cost = -£6.69

break_even_gain = additive_cost / fuel_value_per_1pct
                = £30.00 / £11.66 = 2.6% gain needed

Figures used on this page

Figure	Value	Source	Verified
additive cost per treatment typical	15 GBP	Illustrative: typical retail price of a bottle of heating oil additive dosing one tank treatment, UK retailers, July 2026	2026-07-28
additive efficiency gain conservative pct	0.02 ratio	Illustrative conservative default. Independent verified efficiency gains for domestic kerosene additives are not established; manufacturer claims typically range from 2 to 8 percent and are unverified.	2026-07-28
vat domestic	0.05 ratio	VAT Act 1994 Schedule 7A Group 1, domestic fuel reduced rate	2026-07-28

What affects the result

The claimed efficiency gain. This assumption drives the whole result and it is the weakest link. There is little independent evidence for domestic kerosene additive gains, so we default to a cautious figure and label it unverified. Treat any large claimed gain with scepticism.

How much oil you burn. A percentage saving is worth more on a bigger fuel bill. A home using 3,000 litres has more to gain than one using 800, though the additive cost also scales if you treat every delivery.

The oil price. Saved litres are worth more when oil is dear. That is why the tool uses today's surveyed price rather than a stale figure, so the saving is valued correctly.

Maintenance benefits are separate. Additives may help with tank sludge, water contamination or a smoother burn. Those can be worth having, but they are maintenance, not a fuel saving, and this tool only measures the fuel saving.

What a service does instead. A proper annual boiler service usually improves efficiency more reliably than any bottle of additive, and it keeps the warranty valid. For most homes that is the better place to spend the money.

Additive savings calculator FAQs

Do heating oil additives actually save money?

At conservative, honest inputs they usually do not. On 1,200 litres a year, a 2% gain saves about £23.31, while two treatments cost around £30.00. That leaves a loss of £6.69. You need a gain of about 2.6% just to break even.

What efficiency gain do additives really deliver?

Independent, verified figures for domestic kerosene additives are hard to find. Manufacturer claims typically run from 2 to 8 percent, but these are not independently confirmed. We default the tool to a cautious 2% and label it clearly as unverified.

Are additives ever worth buying?

Possibly, but not usually for fuel savings alone. Some people use them to reduce sludge, protect against condensation in a part full tank, or help an older boiler run more cleanly between services. Those are maintenance reasons, not a saving that shows up on your fuel bill.

What gain would I need to break even?

On the worked example you need roughly a 2.6% efficiency gain just to cover the cost of the additive. Anything below that and you are spending more on the treatment than it saves in fuel.

Should I service my boiler instead?

For most homes, a proper annual service and a clean burner do more for efficiency than any additive, and keep the warranty valid. If you are worried about running costs, spend the money on servicing and on comparing your oil price first.

Why does this tool default to a low gain figure?

Because assuming a high gain would flatter additives and give you a misleading answer, which is exactly the trap this tool is built to avoid. A conservative default keeps the result honest. You can raise the slider to test the manufacturer claim yourself.