Biofuels – dispelling the myths

I heard using biofuels will void my vehicle’s warranty”

As long as you are buying biofuels from a retailer that meets the Government-regulated fuel specifications then you are covered.  If you are using a blend that has only 5 per cent biodiesel (possibly increasing to 7 per cent) this shouldn’t affect your warranty.  However, if you are unsure we recommend you check with your vehicle manufacturer.

Doesn’t bioethanol use more fuel than mineral based fuels?”

You might see a slight increase in fuel consumption (between one and three per cent) as ethanol fuels contain less energy per litre than petrol. However, this can be offset by focusing on efficient driving – things like driving smoothly, correct tyre pressure, and the removal of excess weight or taking roof racks off when not needed. These actions can account for between a 10-40 per cent decrease in fuel consumption[1].  In addition, some biofuels, like Gull’s Force 10, are cheaper than other premium fossil fuels.

“I’ve heard bioethanol can be diluted with water, is this true?”

Whilst this is true for straight bioethanol it is neither desirable nor applicable to the use of blends containing bioethanol. Even small amounts of water in bioethanol blends can cause the bioethanol to separate from the petrol and sink to the bottom of the tank and normal cars cannot run on this. This is why it is important to only store fuels in tanks that are in good condition and that are dry. If you are unsure, get your fuel supplier to check.

“Are there any truths to the rumours that bioethanol causes corrosion issues with motors?”

Retailers like Gull mix in anti-corrosion inhibitors (or additives) with their bioethanol blends.

“Will my engine clog up when it gets cold if I use biodiesel?”

No. If you are buying from a retailer which is Government-regulated (see the suppliers listed on page 3), there shouldn’t be issues. The early versions of biodiesel (or ‘homebrews’ or ‘backyard’ fuels) did not meet the regulated standard and they did create problems, for example when the fuel or engines were cold.

Make a difference now: USE BIOFUELS

Biofuel blends are readily available now – so start using them. It’s a quick and easy way in which we can all reduce the impact of our transportation on New Zealand’s carbon emissions.

For more information check out EECA, who helped provide the great information in this resource sheet.

[1] Biofuels Association of Australia,


Find out more: