Thursday 13 February 2014

Guide to Modern Ethanol Blended Fuels. E10

Guide to Modern Fuels Including Ethanol Blends (E10)

Petrol just isn't what it was in the “good old days”.

First they took away the lead, then the octane reduced over time and finally they added ethanol.

It's fair to say that fuel has changed a great deal, but unfortunately the requirements a internal combustion engine hasn't changed that much.

Higher octane always did and always will produce more power spread over more time when it burns.
Lead always did and always will protect valves from the impact they receive when they hit the seat.

100 % petrol always did and always will resist water uptake and stay in specification longer than ethanol blends.


The lead issues have for the best part found solutions. None of the solutions are as good as lead, but most offer a compromise we are happy to live with in order to save poisoning the next generation with lead fumes as we drive.

If you buy a reasonably modern vehicle it will have harden valve seats, and run on unleaded, Yes it will sound harsh at idle as lots of very hard bits of metal smash against each other in an attempt to let gases in and out of the combustion chamber many times a second.

If your vehicle is slightly older you can have hardened valve seats fitted to the head or run one of the many not quite as good a lead additives to protect your engine. If you keep the engine speed below 4000 rpm and don't overload it by towing, racing etcetera most of the additives will provide adequate protection.


The lowering of octane over time is also fairly easy to deal with as long as you don't mine burning more fuel and sacrificing a little power. A run of the mill engine with a moderate compression ratio will tolerate standard unleaded without any changes. Power will be down slightly and fuel consumption will be up a little. Higher compression engines may benefit from the rather expensive premium higher octane petrol, or the addition of an octane booster. If the vehicle has modern electronic ECU with a knock sensor the clever module will sense the very first signs of knock (pinging) and retard the ignition saving your engine from catastrophic failure. If it doesn't have modern knock sensors but was originally designed to run on a higher octane fuel, it may well be a good idea to retard the ignition slightly if you're running standard grade unleaded with no additives.


For some time now the UK government has allowed ethanol to be added to our petrol at the rate of up to 5%, from 2013 this was increased to 10%. These fuels are not labelled (E10) to warn drivers of the ethanol content, so it is not easy to avoid filling a tank with fuel containing up to 10% ethanol. There is a general belief that high octane premium fuels do not have ethanol, but this can not be proved as it is not labelled, so again it is not possible to tell.

There is lots written on the world wide web about the doom and gloom of E10 and above fuels. To be honest at F2 Motorcycles we took all this with a pinch of salt and thought it would all be OK. However from 1998 to 2013 we had the grand total of one fuel related issue with any of the bikes we know of. It was simply a one off case of badly stored fuel causing all sorts of bad running issues. BUT as we got further into 2013 we got more and more calls about bad running and more and more cases where it turned out to be fuel. Towards the end of 2013 these issues reach silly levels, with some customers in desperation having their bikes trailered to us so we could find the route cause of many running issues. Fitting a remote tank with newly purchased premium grade fuel fixed them, so the conclusion is the E10 fuel is now generally available and causing some real problems across a range of bikes including 2-strokes, 4-strokes, small commuters, large tourer, well everything really.

I don't want to get overly technical as there are already many sites offering lengthy technical arguments as to why E10 is good or bad.

Main problems as far as I can tell.

Ethanol has less energy than petrol, so you will either need to burn more or go slower. E10 contains 3% less energy than standard unleaded so you'll need to burn 3 % more to go as far.

Don't confuse energy with octane. Octane is the ability to resist auto ignition due to compression (knock) and actually ethanol is better than petrol in this respect. This potential benefit is of no use unless you can raise the compression ratio of the original engine.

Ethanol is hygroscopic, that is it readily absorbs water from the air. This is one of the biggest issues, once it becomes waterlogged to the point where it can not absorb more it continues to attract water that simply sits in the bottom of the tank. I've had many cases of customers complaining of water in the tank and asking were on earth it has come from. The answer is the fuel and technically it's know as phase separation.

E10 fuels degrade very quickly. It's hard to say how quickly but the estimates seem to range from a few weeks to a few months. The octane drops, it forms gums, and generally becomes much harder to ignite and produces a great deal less energy when it does. I have had cases, where I was convinced the tank was full of diesel rather than petrol, but it was in fact just E10 that had stood for a few weeks.

Ethanol may attack some rubbers, seals and plastics used in fuel systems. Ethanol molecules are smaller than petrol and can permeate nitrile rubbers causing them to swell, and soften. There is no evidence that it attacks viton. This is why I have viton cap seals made for our range of Jawa motorcycles and fit them as part of the preparation. The originals were cork and E10 appears to attack the glues holding the cork together.

Ethanol may corrode aluminium components in the the fuel system. However (and rather strangely) if the water which ethanol attracts can be kept in solution rather than dropping out (phase separation) test have shown that aluminium corrosion is not an issue.

What can be done to protect your engine from the worse effects of Ethanol.

Firstly insist at every opportunity that all fuel is clearly labelled with the ethanol content E5, E10 etc. It seems ludicrous that we are not allowed to know what we are buying and filling our tank with.

If it's not labelled assume it is E10 (for 2013/14 unless the maximum permitted is changed)

When ever possible buy your fuel from a petrol station which is busy and has a high turn over of fuel. The degradation of E10 starts from the day it is produced, not the day you buy it.

Use an additive, but be careful here, some actually contain ethanol (yes, amazing isn't it). Some are not safe with catalytic converters and will contaminate them leading to huge bills. Some will not mix with other additives for example lead substitutes. If you aren’t certain ring the manufacturer and ask, if they can't answer, buy something else.

Which fuel hose to use with Ethanol blended fuels.

Check all rubber hoses frequently and be prepared to change them for ethanol proof alternatives. Look for any signs of swelling or weeping at joints in the system. There are no additives that can protect against this, whatever they might tell you. There are many companies jumping on the band wagon selling what they claim is ethanol proof fuel hose. Here are a few I have seen for sale.

Silicone – Actually only rated as good 'B' for ethanol (not excellent) and severely effected 'D' not recommended for unleaded petrol.

PVC – Rated only as fair 'C' for ethanol and fair 'C' for unleaded petrol.

Tygon – Rated only as fair 'C' for ethanol and fair 'C' for unleaded petrol.

Viton – Which is the only flexible hose I have found rated as excellent 'A' for ethanol, unleaded petrol, leaded petrol and diesel. We therefore sell Viton fuel hose. Yes it is fairly expensive, but it is very good. 

What additives do we use at F2 Motorcycles Ltd
To protect unleaded valve seats and boost octane we use Millers VSP. It's been proved over time, and many people swear by it. Most importantly we know of no case of it causing an issue. However it must not be used with catalytic converters. It is however fairly expensive.

To protect unleaded valve seats and boost octane at a lower cost we use Castrol Valve Master Plus. Again it has been proved over time, and there are no cases of it causing problems. However it must not be used with catalytic converters.
To protect unleaded valve seats without boosting octane we use Castrol Valve Master. Again it has been proved over time, and there are no cases of it causing problems. However it must not be used with catalytic converters.

To boost octane without addition valve protection, we just buy premium unleaded and pay the extra. No issues with catalytic converters.

To protect against many of the problems with ethanol blends we use Star Tron. You've probably never hear of it but it's been protecting the marine industry in the USA for a few years now. Problems with ethanol are only just starting to surface, so most of the additives will be unheard of, or worse unproven. Star Tron is safe with catalytic converters and mixes with various octane boosters and lead substitutes.

Our experience of Star Tron additive.

As the frequency of fuel issues with E10 increased we started researching various additives. We dismissed any that contained ethanol, any that were brand new and untested and any that were not safe with catalytic converters. We wanted a single, safe, low cost additive that could be added to any petrol vehicle including EFI, carburettor, 4-stroke, 2-stroke, catalytic converter, or not.

We looked at the main issues we had experienced and concluded it was mainly fuel stability (it really doesn’t seem to last more than a few weeks) and water contamination. Early formation of gums and varnishes being particularly frustrating as they restrict small galleries in modern carburettors usually requiring a full ultrasonic clean to rectify. Early signs of fuel degradation can be as minor as slight hesitancy to start, right through to the inability to hold a stable idle even when warm. Accepting no additive can help with the fuel hose degradation we had a short list.

At the time Star Tron did not have a UK wholesaler so we contacted the factory and they kindly shipped us some samples for testing.

Please note these are not scientific tests, and we do not have a multi million pound testing facility, but we do understand engines, and we are sick and tired of problems caused by E10 fuels.

First Test.

1977 Austin Allegro 1500 with SU carburettor. No catalytic converter, no clever electronics. Half a tank of E10 fuel with correct ration of Castrol Valve master Plus, which has been in there for 3 months. This car is not used over the winter so gets to stand with old fuel in it. Attempts to start with untreated fuel proved unsuccessful, but with a battery booster connected it did eventually drag some old fuel from the tank and start. Warm up was difficult and even once up to temperature the idle was erratic. Opening/closing the throttle quickly (to clean it out) had no effect on the idle.

Mixed enough Star Tron for all the fuel in the tank with about a ½ litre of fuel and added this to the tank. |I only pre-mixed so the very small quantity of Star Tron actually made it to the tank as rather than potentially sitting in the filler neck. To be clear, the fuel I used to disperse the Star Tron, was probably worse than the fuel in the tank, as it was dark brown and had been removed from one of the bikes that arrived as a non runner.

Left it a few hours, Star Tron don't say how quickly it works, but I assumed not instantly. Also wanted to let the engine cool.

Attempted to restart, still didn't really want to start, but to be fair the treated fuel was in the tank, not the carburettor. Once it started the erratic idle was back as before, and warm up equally painful. But after a few minutes allowing the fuel to get from the tank to the carb, it was almost like a switch had been flicked. The note of the engine smoothed, the idle stabilised and all was back to how it had been several months earlier when the fuel was new.

This is a single test, but it does seem to give some credence to the manufacturers claims that it stabilises fuel and cleans gums from the fuel system.

Second Test.

Skoda Falicia 1.3 fuel injected hatchback. This is my daily drive but it only does very low miles so a tank of fuel might easily last a month. Started missing and became increasingly hard to start. Got so bad it was missing even when warm at 50 mph. Added Star Tron at the recommended amount and drove for the next couple of days to see if things improved. Nothing improved at all. Still missing and still hard to start. Opened the bonnet and noticed corrosion round one of the coil packs. Removed the coil packs, cleaned everything, put it back together and all missing disappeared. Easy to start and now runs well.
My conclusion is rather unsurprisingly that Star Tron will not fix an underlying ignition fault. Shame, but true.

Third Test.

Ural 750 carburettor engine. Last used in the summer some months ago and left with old fuel in the tank. Almost impossible to start without attaching a bigger battery and winding it over for 30 seconds. When it did start it would not run without both chokes open suggesting the idle jets were gummed up. Added correct amount of Star Tron and gave the bike a good shake to mix it well, like the old 2-stroke days. Attached jump battery and started the engine after much turning over. Once warm, turned the chokes off and it sat there with a perfect idle. Next day it started without the additional battery almost as soon as the starter turned, warmed up quickly and again had perfect idle.

So this is the second time that Star Tron appears to have stabilised fuel and cleaned the old gum out of the jets.

I have now let the bike stand unused for 2 weeks, and today it started first touch of the starter button.

Fourth Test.

250 4-stroke twin with twin carburettors. Not used for several months, but luckily the carbs have handy drain screws in the bottom. Would not start, so drained the carbs of horrid brown old fuel and let them fill up again from the tank. Still would not start, so repeated the drain and refill to try and clean them out. Left it standing for a few hours and drained then refilled once more. Still would not start. Added Star Tron at the correct ratio. Drained the carbs and allowed them to refill from the treated fuel in the tank. Started and ran badly for a minute and then ran perfectly. Star Tron really does appear to restore old fuel and take the gum out of carburettors.

How can F2 Motorcycles Ltd help with Ethanol blended fuels such as E10.

Following my research and the tests above we now stock.

Viton Fuel Pipe, the real stuff, not some Chinese pretend product. Allow enough to route with gentle bends as it does kink easily.
Link toViton Fuel Pipe at F2 Motorcycles Ltd

Star Tron fuel additive, straight from the manufacturers and we only sell the concentrated type.

Star Tron is not magic, it may not cure all fuel related problem, the company makes many claims for their product which we can neither prove or disprove. However, my tests are enough for me to use it in all my vehicles and recommend it. The cost of treating each litre of fuel is far less than buying a premium grade fuel. Premium grade may contain ethanol so buying expensive fuel may not solve the problem anyway.

A simple warning about fakes.

Viton is expensive, if you see a deal that looks to good to be true it probably is.
Star Tron comes in several concentrations, We've seen the weaker concentration being sold as the stronger type. It is very possible to put kerosese in a bottle and sell it as Star Tron if you are a dodgy faker with a label printer, We only source and import our products direct from the manufacturer, so we know it's real. 


  1. Thanks for the info! As for the fuel pipe kinking have you tried using an external strengthening coil of wire? Just to help resist the kinks.

    1. I haven't tried it. Thought about it yesterday, but managed to get the curves correct so it's OK. I reckon if you just couldn't get it kink free your idea would work well.

  2. Someone emailed me saying Harley Davidson do a much cheaper winter additive. Well I don't know what's in it and I have tried to find out, but the forums seem to think it's alcohol (ethanol). One bottle treats 16 US gallons which is 62 litres. The cheapest I can find it in the UK is works out at 11p per treated litre. Star Tron works out at about a quarter of this per litre as one bottle treats 500 litres, so I'll be sticking with the stuff I know.

  3. I used the Harley winter fuel additive in my evo softail for many years... I had a problem with the carb freezing up in the winter since I ran it all year round.
    I have no idea what's in it but have used it in my Ural Dalesman with no odd effects during winter running. However... it's certainly not cheap when compared to Star tron at your price.
    I'll be having a bottle of that I reckon. Thanks for the fantastic info.