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Forewarned is forearmed: E10 petrol

By autotech-nic on September 30, 2019

Raising the current average of 5% ethanol in petrol to 10% is claimed to reduce the equivalent CO2 emissions of 700,000 cars. Yet, policy makers believe that only older/Historic Vehicles will suffer with incompatibility issues; Rob Marshall examines if the government is leaping before it looks and enquires about the real world technical challenges that E10 brings to the typical British car.

Meaningful moves to reduce the environmental burden of the motorcar have to be welcomed, providing that they do not create technical issues that might undermine the ecological goal. ‘Diesel-gate’ is an obvious example of when unrealistic politically-set targets overtake technical reality, which has had a number of negative environmental results. Yet, it cannot be denied that, even when aviation and shipping are excluded from the calculations, transport remains a serious carbon sinner, contributing over a quarter of the UK’s CO2 emissions, according to the Chairman of Smart Transport. Understandably, the government is seeking ways to slash the figure. Prior to her tearful departure as PM, Theresa May committed Britain legally to become the first major economy that achieves net zero carbon emissions by 2050. Considering that the government is being lobbied hard by the vested interests of the British bio-fuel industry that is seeking to increase bio-ethanol production to ensure its own survival, raising petrol’s bio-ethanol content is being seen by some quarters as a quick and easy carbon-slashing first-step, with no apparent technical disadvantage. Is it really too good to be true, or is this issue shrouded in smoke and mirrors?

Why E10?

Currently, UK petrol contains an average of 5% ethanol (reputed to be closer to 3%). This ‘E5’ blend was introduced during the previous decade and was reported to be the maximum recommended percentage at which any technical difficulties experienced by even Historic Vehicles (i.e. those over 40 years-old) would be negligible. Various subsequent legal directives have encouraged an increase in this figure to an average of 10% (E10). Although delayed in the UK, E10 has been adopted by various EU member states but is especially widespread in North America.

The Department for Transport (DfT) told AT that no decision has been made about whether, or not, to introduce E10 at the time of writing. Yet, last year’s E10 consultation is part of a plan to collate information and educate the public about petrol (and diesel) bio-fuel content, should E10 be launched formally, possibly to avoid a repeat of the disastrous and almost hysterical boycotting of E10 at its introduction in Germany during 2011. The recent relabelling of petrol pumps to emphasise and clarify pump fuels’ bio-fuel contents has come about from separate legislation but it helps to enable familiarity, should E10 appear on these shores. As part of our research, AT was told by an influential bio-ethanol industry figure that ethanol advocates must:

“Point to the real-world overwhelming evidence that E10 is innocuous”

Yet, if this were the case, why are car manufacturers being quoted as calling E10 “harmful” if a car is misfuelled? Plus, the German motoring organisation, ADAC, reports that a single tankful “can cause serious, lasting damage” should it be used in a non-compatible vehicle. AT‘s technical discussions with various lubricant and fuel/oil additive experts over the years have revealed that the increasing percentage of bio-fuel present in petrol (and diesel) poses a number of technical challenges, even on vehicles that are stated as being compatible. E10, therefore, is harmful but its effects can be managed. Should the new fuel blend be introduced, you will need to advise your customers accordingly, because the increase in ethanol will have technical implications that you may have to address, either in a repair, or a preventative maintenance capacity.

Corrosion of the fuel tank and brass carburettor parts are the main challenges for Historic Vehicles. Rubber fuel lines also become brittle, split and leak fuel, as seen here.

E10 compatibility – a legal, not technical, statement

The DfT has recommended that the official description for E10-compatible cars are those that, broadly, have been made post-2000. A more detailed list from manufacturers stating E10-compatibility can be downloaded here. Debates in UK Parliament about non-E10 compliant vehicles have tended to revolve around ethanol deteriorating certain metal and rubber components on Historic Vehicles and not those parts fitted to the vast majority of newer, more common petrol cars. Even so, should you maintain/repair classics for enthusiast customers and you are concerned about ethanol, specialists should be able to advise you. Consult the FBHVC advice on fuels about using E10 on classic cars and motorcycles.

However, Dr Ivo Wengraf of the RAC Foundation told AT that car manufacturer categorisation of ‘E10-compatibility’ tends to err on the side of caution for warranty and not technical reasons. Even so, as explained in what follows, workshop technicians cannot presume that all post-2000 vehicles, including those certified for E10, will not experience consequences from running on the fuel. Dr Wengraf’s 2018 report matches vehicle manufacturer data with DVLA registration data and identifies that modern cars from MG-Rover, the Volkswagen Group, Mazda, Nissan and Toyota, are likely to be the most numerous E10-incompatible vehicles on our roads in 2020. It also breaks-down the number of affected cars by UK region, so you can deduce by how much your area is affected.

Gasoline Direct Injection (GDI) engines introduced a number of precision made parts but the aluminium components on some first generation GDI cars, made from around 1995-2008, can be attacked by E10, causing premature failure. Consult and download the ACEA’s E10 compatibility list for more information.

Does E10 harm engines seriously?

No. The 1981 study, published by the North American Journal of Automotive Engineers, ran new 2.3-litre petrol engines for 20 hours under mid-load conditions and concluded that E10 did not increase engine wear levels significantly over regular US unleaded gasoline of the time. Interestingly, it did notice greater water content in the oil after the test and slightly elevated levels of camshaft follower, valve guides and no2 piston ring wear but these were not deemed to be significant. However, detail changes in modern petrol engines have seen them become less tolerant of combustion deposits and this reduces efficiency and increases wear if not addressed.

Aside from this consideration, while E10 does not harm engines directly and immediately, it can do so indirectly, by affecting the fuel injection and lubrication circuits adversely in real-world conditions. The reduced capacity of these systems to work at maximum effectiveness also results in premature engine wear and efficiency reductions that, in turn, will raise harmful emissions, which would undermine the positive environmental claims made about E10 by the bioethanol industry.

AT has been directed to studies of vehicles running on E10 by the DfT but we questioned if they were representative of real-world conditions, because the vehicles used were not old enough to be an accurate representation of the UK (and EU) car parcs. The DfT responded, by informing us that new car models are Type Approved tested for emissions and fuel consumption results in Europe using E10 but the DfT could neither confirm if E10 was used to Type Approve cars of average age in the UK (standing at almost 8 years-old, according to GiPA), nor if it had conducted any of its own research about the effects of E10 on such vehicles that experience UK climates and drive-cycles, including a typical driving commute of 7-10 miles. With apparently no independent UK-derived research available, we have had to approach the technical experts from various additive and lubrication companies mainly in North America and Europe for their findings.

The most prevalent known family of engines that are E10-incompatible is Volkswagen Group’s FSI range.

E10 and corrosion

Gilbert Groot of JLM Lubricants in the Netherlands (where E10 is available) confirmed that ethanol has corroding effects on metal surfaces and dries-out rubber hoses. These material incompatibility issues are more prevalent in Historic Vehicles (i.e. those over 40 years-old), many owners of which had replaced rubber fuel lines, since E5 was introduced. Owners of other machinery (such as boats and certain motorcycles) have had issues with fibreglass fuel tanks, because ethanol within the petrol dissolves the resin.

As direct injection petrol engines (GDI) introduced high pressure technology that was inherited from diesel engines to increase power and reduce CO2, they also became less tolerant of fuel specifications deviating from those used when the car was new. Early GDI engines from the Noughties seem to suffer especially from material incompatibility problems in their high pressure systems. In 2011, ADAC found that the high pressure fuel pump (which we understand was renewed at the start of the trial) of its E10-incompatible 2.2-litre Opel/Vauxhall Signum test vehicle failed after 27,000 kilometres of running on 10% bio-ethanol. It is thought that aluminium components within the high pressure fuel pumps on early GDI vehicles are vulnerable to ‘corrosion attack’ and ADAC found that this can be triggered after a single refuelling with E10, which becomes unstoppable in most cases. The most common example of modern fuel system E10 incompatibility rests with the first generation FSI engine used by the Volkswagen Group brands, many of which are still on UK roads, according to Dr Wengraf’s report.

While ADAC reported in 2016 that it was unaware of any car manufacturer compensating owners of E10-compliant cars for problems attributable to using E10, this should not be taken as a presumption that zero issues exist.

At the engine top

According to the AMF’s (Advanced Motor Fuels) report on E10 ethanol properties, E10 contains sulphates and copper that introduces gum formation and promotes fuel injector deposits. JLM Lubricants highlights that, aside from acting as fuel, petrol possesses a lubricating mechanism for the mechanical components that are in contact with it. As ethanol lacks any lubrication properties, this might have a negative effect on the durability of fuel system components, unless, of course, extra additives are blended with the fuel at the refinery to counteract it. Consider also that ethanol can hold water in suspension and is hygroscopic; these properties alone can increase the risk of corrosion within the fuel system.

From its experience of the North American market and fuel blends, BG Products has found that post-combustion deposits increase, because the additional oxygen present within E10 accelerates the aging process of the fuel. It has developed its 203 and 213 additives accordingly to help stabilise the fuel and keep intake manifolds, ports, valves and combustion chambers clean and free of, what it says are, “damaging deposits typically caused by ethanol”.

ITW Additives International, makers of the renowned Wynn’s Professional and Forté ranges concurs and told us that ethanol-blended petrol tends to be more acidic. The resultant contamination promotes incomplete combustion that causes more deposits to be circulated via the exhaust gas recirculation (EGR) and the intake systems, increasing contamination in those areas. Consequential issues include higher exhaust emissions, poor running, catalytic converter failure, sticking inlet valves, plus EGR valve/swirl-flap blockages/restrictions.

BG Products adds that the greatest weakness of ethanol blended fuels is their susceptibility to ‘phase separate’ into a petrol (top layer) and an incombustible water-ethanol gloop (bottom layer). The issue is not helped by ethanol’s ability to hold water in suspension up to a certain level before it separates. ITW Additives International revealed that it has found that natural degradation of E10 occurs within 4-6 weeks, before phase separation occurs and running a modern engine on the degraded fuel can lead to lacquers and varnish contaminating the fuel injectors, which affect their spray patterns, leading to incomplete combustion and the creation of larger deposits that also contribute to engine running issues.

A suggested way to avoid these issues is to brim and empty the fuel tank regularly but it is feasible that certain plug-in hybrid cars with a reasonable electric-only range (such as the Mitsubishi PHEV) may not empty their fuel tanks before the fuel either ‘goes-off’, or the phase separation process begins. Interestingly, the Chevrolet Volt/ Vauxhall Ampera hybrid models (sold as the same car under different badges between 2012-1014 but, admittedly, they were not volume sellers in the UK) had a fuel maintenance mode to encourage the engine to burn old fuel but this activates only after a year has elapsed. The issue of fuel separation, therefore, may become more of a real-world problem for the latest and forthcoming Plug-In Hybrid cars that can travel greater distances in electric-only mode.

Due to the different combustion chemistry, the power output of ethanol is slightly lower than of petrol, so fuel consumption increases slightly. Yet, the difference between E5 to E10 petrol is barely noticeable. ADAC has calculated that the typical motorist will see a fuel consumption increase of approximately 1.5%.

A number of our sources agreed that driving styles and conditions influence the technical challenges that E10 brings. Yet, we are aware that the DfT has been advised that UK real world tests were unnecessary on E10, because the Americans, French, Belgians and Finns have done it for us, with live subjects”. Unfortunately, this presumes that overseas driving habits and journeys are the same as ours. While France constitutes the largest E10 market in the EU, it accounts for only 38.5% of petrol sales; that figure plummets to 13.4% in Germany (based on 2017 figures). Therefore, it is possible that real-world technical issues, attributable to E10, may not be prevalent as those experienced in North America, where 95% of gasoline there contains at least 10% ethanol.

Yet, comparing US conditions with the UK is also problematic. BG Products in the UK and North America told us its research revealed that the average UK mileage is 7,400 annually, compared to 13,400 in the US and, because US passenger vehicle fuel tank capacities tend to be smaller than those in the UK (and EU), it is not an unreasonable conclusion that North American tanks are replenished nearly twice as frequently. Both BG Products and Lucas Oil revealed that North American drivers tend to change their oil more often (it can be as low as every 3,000 miles but tends to be around 7-10,000 miles, or twice annually), compared to the recommended drain intervals of between 10,000 and 20,000 in the UK/EU, or once annually. More regular fuel tank replenishing and oil changes will help diminish many of E10’s negative effects and indicates that making presumed direct comparisons between the US and UK will not yield accurate technical conclusions.

Be wary of presuming that a range of cars is compliant, because there can be some exceptions. Volvo, for example, states that post-1976 cars are E10-compatible. Yet, it offered two 1.8-litre variants of its V40 and S40 models until 2004; the GDI version (which was supplied by Mitsubishi and shared with the Carisma model) will be damaged severely by E10.

Getting to the bottom of things – the sump

According to the Royal Society of Chemistry, as bioethanol is being blended with gasoline at increasingly higher concentrations, the accumulation of fuel in the crankcase/sump could be significant. Therefore, engine oils must be used to combat ethanol’s propensity to undermine a vehicle’s lubrication system.

David Wright, Director General of the UK-based Verification of Lubrication Specifications (VLS) adds that, because biofuels are less stable than other fuels and oxidise easily, increased engine oil thickening results and this restricts lubricant flow.

He adds that ethanol also vaporises in contact with high temperatures, supporting the possibility of greater quantities of fuel contaminating the oil.

While Lucas Oil of North America states that much of the fuel that enters the sump evaporates at higher temperatures via the crankcase breather, ITW Additives International states that this is harder for E10’s ethanol content, which can hasten engine oil deterioration. Lucas Oil agrees but adds that ethanol does not mix fully in motor oil and, in theory, high levels of fuel dilution could allow sliding metal parts to be exposed to surfaces wet with ethanol, rather than motor oil. While the likelihood is small, it is possible in the real world.

GDI engines are prone deposit build in their intakes, which restricts air flow and engine efficiency. E10 is known to increase the rate at which these deposits build, so offering an intake cleaning service might be beneficial.

Interestingly, Lucas Oil revealed that ethanol is implicated for causing higher levels of sludging, created by oxidised engine oil and combustion deposits leaving the oil and attaching themselves firmly to the engine’s internal metal parts. However, the company’s Technical Director concludes that this assertion is debated and there is no authoritative real-life evidence of a link between ethanol and an increase in sludging, despite the chemical theory supporting it.

While it is well-established that short journeys and low coolant/oil temperatures increase oil contamination rates, Phil Dugmore, ITW’s British Technical Services Manager, reports that we could see an increase in contamination build as ethanol content in fuel increased. Oliver Kuhn, deputy head of LIQUI MOLY’s oil laboratory in Germany highlights that Hybrid vehicles may also suffer from increased deposits in their oil, when driven mainly under electric power, while the E10-fuelled combustion engine runs only occasionally.

LIQUI MOLY adds that ethanol’s 4% water content leads to an increased formation of acids, which will increase oil acidity, decrease viscosity and hasten oil degradation further. While this sounds alarming, both Mr Kuhn and Mr Wright agree that these issues do not pose a problem for modern engine oils, because the latest lubricants have been formulated to address these technical challenges for ethanol blends up to 20%. However, as Mr Wright revealed that previous blends of lubricants would have been designed for fuels that were available at that time of their development, it could not be confirmed whether any older oil formulations (such as 10W40 semi-synthetic, or 5W40 fully-synthetic) could protect older engines from increased engine oil degradation issues that E10 will introduce. LIQUI MOLY has found that some cheap oils are on the market that do not comply with the updated specifications for E10 but the VLS says that it helps to ensure that latest lubricants are used with appropriate fuel and engine developments. Naturally, using more ‘ethanol resistant’ oil that possesses a thinner viscosity in an older engine could cause severe damage. Additionally, using older specification lubricants in newer engines is just as unwise.

Unless resolved by the fuel blenders, E10 phase separation could become a serious issue for not only cherished stored cars but also modern plug-in Hybrids. This Mitsubishi Outlander PHEV can be driven up to 28 miles in electric-only mode, according to the stricter real-world WLTP tests, meaning that the same fuel could be in the tank for many weeks, or longer.

What should technicians do?

Using E10 in a non-compliant modern vehicle has been proven to be immensely damaging. Advise your customer whether, or not, their car is officially E10-compatible. Where E10 can be used, instruct the customer accordingly, dependent on their driving habits. More regular fuel fills are recommended, to keep the tank contents fresh before deterioration and phase separation occurs.

At service time, ensure that the crankcase breathing equipment is in good condition and use a quality oil flush during each oil change. Always use decent, branded engine oil, of the appropriate specification. The advice from Lucas Oil in the US to UK garages and drivers is that it is wise to consider more frequent oil changes and make minor adjustments in driving habits, such as consolidating several small trips into fewer longer ones. ITW Additives International agrees and adds that regular maintenance and cleaning of the fuel and oil systems will help to reduce the effects of ethanol. Using a fuel additive at service time, to help particularly with fuel injector lacquering, is a useful preventative measure, as is monitoring the intake and EGR systems for increased deposits. AT will be looking at the growing market for GDI petrol intake cleaning shortly.

We must emphasise again that no formal decision has been made by the DfT on E10’s introduction. However, as the practical in-service issues of E10 appear not to have been discussed in-depth by our policy makers, it is best that the aftermarket technician is kept aware of the potential issues that E10 can cause. We have agreed to supply the DfT with some of our sources’ details, who are willing to help with any future consultations before a verdict on E10’s UK future is made.




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