Classic cars and E10 fuel

E10 Fuel – What is it?

E10 fuel has been in both the classic and mainstream press a lot recently. Pump fuel is made up from an awful lot more than just fractionally distilled mineral oil, part of that is ethanol. Before September 2021 the UK standard for ethanol content in normal unleaded fuel was less than 5%, and therefore labelled as E5.

Ethanol is a fuel produced from crops, by using it we reduce the carbon footprint of every tankful. The government is keen to increase the amount of ethanol in our fuel because it decreases our dependence on OPEC nations and it could reduce the national CO2 emissions by 750,000 tonnes a year. In September 2021 the UK standard for ethanol content will increase to 10% on standard unleaded, but will remain at less than 5% for super or premium unleaded.

What is the issue with a higher ethanol content?

Firstly, there is nothing we can do about it. Legislation is passed, so there is no use puffing your chest out and getting all annoyed with the establishment.

Secondly, super or premium unleaded will continue for a minimum of the next 5 years, so, in the medium term, as long as you fill up with Super everything stays the same.

Thirdly the odd tank full will make no difference if you can’t find Premium. Any issues that may occur are more from long term use or storage.

However, there are issues with Ethanol, so let’s look at them one by one and see what you can do to mitigate them.

Water

Ethanol is hygroscopic, which means that it attracts moisture from the atmosphere. The water separates in the fuel mix and then corrodes anything ferrous. This means the inside of steel fuel tanks, carb pots and steel fuel lines. The rust particles break off, get swirled around your fuel system and then block up in your fuel filter, carburettor or injection unit.

This is a particular problem for classic cars. Because we don’t use them all the time, the fuel has more time to absorb water. The average classic does less than 1000 miles a year, which means that they use less than 50 gallons of fuel. The average modern car uses about 350 gallons a year which means the fuel inside is 7 times newer. It simply does not have the time to absorb the water. Now this has been a problem for years, it is just going to get a little worse, so what can you do?

1. Keep your fuel fresh – Try to use the fuel you put in the car within two months.
2. Install an inline filter at the tank and carburettor end to catch any debris
3. Change fuel filters every year as part of your regular maintenance
4. Only store a car with full tanks over a prolonged period if you use a stabiliser additive in your fuel
5. Store your car in an environment with low humidity, around 45 to 60% is about perfect

Density

The density and calorific value of E10 fuel is be different from E5. In the same way as you get a difference in performance running regular or super unleaded fuel there is a difference between E5 and E10. 

If you are going to use E10 fuel all the time then you may well need to adjust the fuel/air ratio and the timing of the engine to suit. Your engine will probably run lean, but well within the parameters of being able to adjust the difference out. Our advice is that when you come in for a regular service, have whatever fuel you are most likely to use in the car. That way, when the mechanic tunes it up, he is doing so using the ‘right fuel’.

Acid corrosion 

Ethanol contains bacteria which produce an acid that is corrosive to some rubber components. This is a fact, but we have had Ethanol in our fuel for donkey’s years, Europe have had E10 for a decade and the Americans have been using E85 since the 1960’s. So it is not a new phenomenon. Rubber hoses perish over time and are almost always overlooked when it comes to maintaining a classic.

Ethanol will accelerate the degradation of the rubber pipe in your vehicle, but it is way more likely to fail, simply because it is OLD! If you can’t remember changing fuel line, then it is probably about time you do it.

Rubber fuel line

There actually isn’t much rubber line in most fuel systems. Generally there is a flexible pipe from the fuel tank/pump to a ‘hard line’ that runs up to the engine bay, from there there are a few sections of rubber pipe that run from the hard line to the regulator and onto the carbs.

Replacing it is not an expensive job. If you can do it yourself, new E10 approved flexible fuel line will cost about £15 for 1 meter in any Auto Factors in the country and will take you a couple of hours. Budget between £100 and £125 in labour to have it done with us or any other reputable classic car specialist.

Rubber ‘O’ rings and gaskets and floats

There are rubber ‘o’ or sealing rings in both carburettor and injection cars. They are way more likely to fail because they are 20 plus years old than simply down to another 5% of ethanol in the fuel. As part of your maintenance, keep an eye and nose on the fuel delivery components in your engine bay.

If you can smell fuel, you have vapor present and therefore the beginnings of a leak. It needs to be tracked down and repaired. New old stock carb and injection kits should be avoided like the plague. The rubber is old, and although they might look OK are probably no better than the ones you are taking off. Make sure you are buying something that has been recently produced.

Classic Collective Rebuild Carbs and Injection Systems

Both carburettors and early injection systems such as Lucas or Bosch Jet-Tronic will need rebuilding as part of general maintenance every 10 years or so. This work helps improve performance and fuel consumption. However, what it really does is keep the whole thing safe and reliable

We can strip and rebuild both carburettors and injection systems. We use OEM grade components making sure you get the very best out of your engine.

Proactive protection

There are fuel additives on the market that you can mix when filling up your tank.