Fuels and understanding them is vital to our businesses, yet the myths and legends surrounding petrol have caught out many in the industry. Gary Fooks, Chair of Blue Sky Alliance, has designed this article to educate office staff, an apprentice or settle a bet. 


There exists a myth chat fuelling a car with higher octane fuel will deliver more power. The truth is no, not really... well maybe if...

Octane is not energy or power and certainly not 'zoom'. So co sort out the tangled mess of confusion let us first get a few facts. One way to design an engine to deliver more power for its size is to compress the fuel/air mixture harder - a high compression engine. Compress a spring harder and it will release more energy when you let it go. Compress fuel in an engine's cylinder and when it is ignited by the spark plug at the point of highest compression, more energy is released.

That might sound great, but when regular fuel is compressed in a hot, high compression engine it ignites before the spark plug is timed to do its job.  This means the compression, rather than the spark, sets off the fuel ignition. This is called 'pre-ignition' and can generally be heard as a 'rattle' in cars when they are labouring in too high a gear. It is not good for engines and is no way to drive.

Octane is the ability of a fuel to resist pre-ignition. The higher the Research Octane Number (RON), the higher compression engine it can serve. It is not just Ferrari - ordinary 1500cc cars from European manufacturers are tuned for higher compression and need 95 octane fuel. 

To sort out the confusion I raised at the beginning: if you use regular fuel in a car designed to run on 95 octane petrol, then the electronics will take over and effectively hamper engine performance, slightly retarding the ignition, so you don’t get the nasty effects of pre-ignition. Drain the tank and fill it with 95RON and yes, you will get more 'zoom: or rather, you get the performance it was designed to deliver in the first place, before we knobbled it with low octane fuel.

It is important to note that the opposite is not true. Putting high octane fuel in an engine designed to use only regular fuel will not improve performance and is a waste of money.

In the power equipment world, I'm not aware of any engine that needs, or would benefit from, high octane fuel, although that may change with the implementation of emissions regulations in 2018 as different spec engines are introduced. However, my initial thoughts are that the new spec engines will still only require regular petrol.

In conclusion octane is not power, unless your engine is designed for (needs) higher RON fuel, you are just wasting your money.


Given my work on the introduction of emissions standards I’m sure chat I have been called "chat greenie guy” (and probably worse!). I'll cop chat, but surprisingly, I won't buy ethanol for my car, boat or power equipment. Not E10, and not E85.

I don't give this warning lightly because 10 per cent blended Ethanol fuel (E10) has some real benefits; it oxygenates the fuel, meaning it burns cleaner with less pollution. It adds octane - pure ethanol has an octane rating of about 129RON. 

Reducing our reliance on imported petrol by 10 per cent sounds like a good idea too. So, what’s the rub?

The net environmental benefits don’t seem to stack up. Sure, there would be less air pollution in Sydney traffic, but more pollutants are produced when we grow, fertilize and harvest the sugar, convert it into ethanol and truck it to the city. Needless to say, the Greens are not championing ethanol. Rather it is the political baby of certain farming sectors, the Nationals and the Katter Perry in particular. Politics and not environment is the reason why we have mandated E10 in Queensland and New South Wales. 

An issue with Ethanol is that it is a solvent. Because it is such a powerful solvent it dissolves components of fuel systems, such as fibreglass (Glass Reinforces Plastic or GRP) fuel tanks, some plastics as well as many elastomer (rubber-like) materials, specifically some fuel lines and even corrodes aluminium fuel tanks. 

As soon as a leak develops so too does a fire risk. Even if a fire doesn't eventuate, a leak will mean a powerful solvent is melting away the surface under the leak.

There is an even greater risk for older machines. As the tech manager of one Engine Company put it: ethanol is going to liberate dirt and residue in your fuel system that you never knew existed.
Most of the fuel tank and fuel line compounds dissolved into the   E10 are in solution and not suspension, which means that they pass through the very best fuel filter. Once inside the engine and fuel injectors they turn back into solids, resulting in terminal damage. 

Almost all engine manufacturers will advise that their engine will cope with up to ten per cent Ethanol; but that means clean E10. No warranty will cover the damage caused by fuel mixed with dissolved elastomers, plastics or GRP.

The Haines family business has been on top of this risk for years. They use only ethanol resistant components: fuel tanks, lines, filters and fittings and in addition, put a warning label on every fuel cap seating "do not use E10': This seems a wise strategy.

Ethanol has another unfortunate property. It is hygroscopic, meaning it attracts and bonds with water. In a process called 'Phase Separation', the ethanol water mix separates from the petrol and sinks to the bottom of the fuel tank. No amount of stirring, shaking or additives will reverse the process. Once enough separated ethanol has built up on the bottom of the tank, the fuel pickup delivers a dose of neat 100 per cent ethanol into a fuel system and engine chat can only cope with a ten per cent dose. This is believed to be the cause of several catastrophic machine failures. All it takes is humidity and time, and the process is more likely to occur with a machine chat sits in the shed for long periods, than in a car driven daily.

Short Shelf Life

Normal petrol has a shelf life of one to three months -  shorter in higher temperatures. This is because the lighter components of the petrol cocktail evaporate off, leaving the thicker pacts or gums behind. Too many of us know what that does to an engine. Old fuel simply gums up an engine, needing an expensive, time consuming repair.

Ethanol is very volatile, meaning it converts from liquid to vapour readily. E10 goes 'off' far more quickly than regular fuel. Again, this is especially quick in warm weather, or a hot garden shed. This short shelf life was the main concern of the experts I have spoken with at fuel companies. I have contacted BP, Shell and Caltex during my research and all have advised chat small engines, and especially boat owners, should not use an ethanol mix fuel. Full stop.

E10 – Not Cheap Enough

What concerns me most is chat consumers are being fooled into buying E10 based on price, because it is commonly three CPL (two per cent) cheaper than regular unleaded fuel.

Ethanol is a 'thinner fuel' with about 30 per cent less energy than regular fuel. This means you should get about three per cent less mileage out of a tank of E10. Ethanol is only two per cent cheaper and therefore not value for money.

Like most servo's, my local only has a fixed number of storage tanks and pumps. So, when the mandate came in we lost regular unleaded fuel. This means it is either E10 or premium for an extra 16CPL. No wonder the oil companies aren't protesting. But I am. I am paying 16CPL more in “Katter Tax” for fuel that won’t benefit my engines, but I buy it just to avoid the risks of ethanol. 


Ethanol is the most common biofuel around the world. Not just mixed with petrol but up to 15 per cent with Diesel.

On the horizon is BioButanol, a fud or fuel supplement that is also brewed from farm products but without the drawbacks of ethanol. BP and The Dow Chemical Company have a pilot plane running in the UK, so serious work has begun, however any resulting change at the pumps would be a decade away.

Australian Fuel standards are once again under review, this time in tandem with a review of vehicle emission standards. The Discussion paper 'Better fuel for cleaner air' can be read at

The focus of the review will disappoint some industry experts who have concerns over the forthcoming emission standards which are based on the US standards. In practice this means US spec engines, but trying to run these products with the higher viscosity Australian fuels.

The focus of the Fuel Standards work is on:
•    Sulphur content a perennial topic
•    Octane levels - dropping regular is an option under consideration
•    Cetane levels in diesel the equivalent to octane
•    Esters - especially MTBE used as an octane enhancer but seen as a groundwater contaminant and banned in some jurisdictions

With the Government working to a firm dace of 1 July 2018 for the commencement of engine emissions standards, the clever companies will be running at full speed now, importing samples of US spec products and running field trials on a range of Australian fuels. Ironing out bugs now, getting the changes into production and on a ship to arrive in June 2018 is a lot of work to be achieved in a short time.

Thanks to Garry Fooks (Power Equipment Australasia) for this article.   

How To's - General Information | How To's - Lawn Care | How To's - Brushcutters | How To's - Chainsaws | How To's - Hedge Trimmers | How To's - Mixing Two Stroke Fuel