Main content | back to top
Myth Busting – the Facts about Ethanol in Petrol
Ethanol is a renewable non-fossil biofuel produced in Australia, and other countries, by either taking one of the by-products of the sugarcane industry (molasses), wheat or other grains such as corn and processing it to produce ethanol.
Ethanol, when used in vehicles, can help maximize the performance and acceleration potential of many modern cars. It is a cleaner burning, renewable component that helps reduce Greenhouse gas emissions. It also helps to achieve low benzene and sulphur levels.
Shell has over 25 years of global experience successfully formulating and testing ethanol based fuel in markets including US, Sweden and Brazil, selling over 1 million tonnes of ethanol-based fuel each year.
Myth 1. Ethanol burns hot due to an earlier ‘pre-detonation ratio’ (i.e. it explodes too soon) and can corrode engines over time.
Ethanol has a high octane (Research and Motor Octanes) and as such ethanol based fuels have a natural tendency to resist compressive precombustion in engine combustion chambers. Its incorporation into fuel, in controlled quantities, will have the effect of lifting octane and allowing exposure to greater heat and compression in engines without 'pinging' (precombustion).
The potential for corrosion due to ethanol has, in the past, been due to improper use by other retailers of lower quality ethanol at inappropriate blend ratios without corrosion protection.
Along with this standard, Shell fuel-grade ethanol contains a corrosion inhibitor additive to ensure that corrosion due to trace impurities naturally present in ethanol is minimised.
Myth 2. Ethanol fails to lubricate the engine like petrol so there is a potential for pistons and other moving parts within the combustion chamber to ‘seize up’ over time.
Lubrication of piston rings in spark ignition 4 stroke engines is a result of traces of lubricating oil trapped between rings and combustion chamber wall. It is not due to the lubricating qualities of the motor spirit, so the impact of ethanol in this part of the engine will be negligible.
Lubrication of other components such as fuel pumps of moving fuel system components is, however, dependent on the lubricating property of the fuel. In these cases ethanol contents of up to 10% have not been shown to cause excessive / noticeable wear in any other countries where Shell markets ethanol containing fuels.
Shell has extensive experience with biofuels and is the largest global retailer of ethanol containing fuels. Shell markets ethanol containing petrol in several countries and has no records of adverse lubrication issues relating to these fuels. Also, a review of the available literature / studies also does not indicate that fuel system wear due to lack of lubrication is an issue.
Myth 3. Ethanol can corrode fuel lines or anything rubber, including seals.
Ethanol in high concentrations has been known to affect some plastic and rubber fuel system components. However, it is advisable to check the FCAI web site - opens in new window or contact your vehicle’s manufacturer to determine if there are any compatibility issues with particular makes and models.
Myth 4. Ethanol always reduces fuel economy.
Like regular Shell Unleaded, Shell Unleaded E10 contains Shell's exclusive Fuel Economy Formula, which is designed to help improve fuel economy by reducing efficiency losses caused by engine deposits.*
Ethanol has a lower energy value than regular petrol, however, when ethanol is blended into petrol at 10%, its effect on fuel efficiency is reduced proportionally. In fact, driving style and driving conditions will have a greater impact on fuel economy than the presence of 10% ethanol.
* Based on tests using fuel without additives and may vary by vehicle.