AFTERMARKET FUEL AND OIL ADDITIVES:

Such is the marketing hype that goes with many of these products you may be led to believe that the use of fuel and oil additives can transform a rattly high mileage old motorcycle that has been starved of decent fuel and regular oil changes into a liquid smooth rocket capable of breaking land speed records in silence.

Of course, unfortunately, this is not the case. But that does not mean the judicial use of some products in some engines will not bring some benefits, even though at a cost to your wallet. It is just that you should not believe everything you read and should select carefully which products you use and when, and without the expectation, as some makers claim, that they can repair worn components. They may contain some clever chemicals but they do not contain spanner-wielding nanobots.

In this post we deal specifically with fuel additives. Keep an eye on our website for the follow-up post on oil additives.

Fuel additives:

While most oil additives are not worthy of the hype that surrounds them and are not worth the money they cost, the same can not necessarily be said of some fuel additives. For the most part they shouldn’t be necessary, because you should be riding your bike regularly and throughout the year, shouldn’t you? Why wouldn’t you? But the fact is that for many people there are long periods where our bikes sit neglected, in a garage if the bike is lucky, or outside under a cover if not, and in those conditions the occasional use of the correct fuel additive may benefit.

There are three types of fuel additive:

1          Fuel stabilisers.

2          Fuel system cleaners.

3          Octane boosters.

Fuel stabilisers and fuel system cleaners seem like a good idea on the face of it, and the theory is hard to argue with, and is the reason why they are already present in all the fuel we buy. Typically the market has also responded to concerns about fuel by supplying a vast array of products dedicated to stabilising fuel degradation, preventing phase separation, and cleaning and protecting the fuel system. But do these additives really work as well in practice as they claim to on the packaging, and are they really necessary? Or is it all just more pseudoscience and psychobabble created by marketers to part well-intentioned bikers from their hard-earned cash? Read on to find out.

Octane boosters should rarely be required and for the most part can be left alone and forgotten about, as I explain later.

The effects of ethanol in fuel:

It is a well-known fact that the fuel we buy at the pumps contains ethanol, and this is the main cause of concern and the issue that most users seek to address. But is it a concern? That depends on the circumstances, and how much ethanol there is. To clarify, a fuel marked E5 has up to 5% ethanol, E10 has up to 10%, and E15 up to 15%. So at least it is easy to tell before you fill up, and that gives you a choice of whether you use the fuel from that supplier or not.

At present the standard fuels in the UK are premium unleaded 95 RON E5 (though 95 RON E10 can be sold), and super unleaded 98 RON E5. But be aware that in an effort to reduce CO2 emissions the government is raising the required ethanol content of premium unleaded fuel from E5 to E10 in September 2021, as they reckon it will bring about a CO2 emissions reduction equivalent to taking 350,000 cars off the road. As a biker I would much prefer it if they just did that, there are far too many of them.

As a precaution it is worth checking that your bike will be OK on E10, and this can be done by looking in your handbook or for a label on your fuel tank, asking your dealer, or using the Government checker, though this does not cover all makes. Otherwise you may have to fill up on the more expensive stuff.

So what is ethanol and what does it do? The answer to the first question is easy, ethanol is alcohol. But whatever you do don’t drink it. What does it do? The answer to that is more involved, and there is good and bad.

The good:

• Ethanol is used to raise the octane rating of fuel - the ethanol molecule contains oxygen, which raises the octane rating and so allows the fuel to resist detonation, so it burns rather than explodes.
• To raise the octane level using ethanol is cheaper than further refinement of the petrol, so fuel costs can be kept lower - think of the difference in cost between 95 RON and 98 RON and you see what I mean.
• Fuel with ethanol burns more cleanly, resulting in lower CO2 emissions.
• A lot of ethanol is made from corn and sugarcane, which absorb carbon dioxide from the atmosphere as they grow.

The bad:

• Ethanol is hygroscopic, meaning it absorbs moisture from the air, which forms water in the fuel. This hygroscopicity makes storage during production, transportation and use difficult, as all forms of storage must be sealed. If moisture does get in phase separation can occur, but this takes a long time, probably longer than it takes for the fuel itself to degrade. If phase separation does occur the water separates from the fuel, and as it does the ethanol sticks to the water. As the ethanol is then no longer part of the fuel it reduces the octane rating back to what it was before the ethanol was added, and then your engine starts knocking.
• Water and petrol don’t mix and if there is enough water it sinks to the bottom of the tank, where the fuel outlet is. In a worst-case (but unlikely) scenario, if you have a tank that does not seal very well and sits outside over a long winter in moist-laden air, the ethanol absorbs the moisture, phase separation occurs and the water sinks to the bottom. So when you come to start the bike in the spring it doesn’t because water instead of fuel is drawn from the tank and unfortunately bikes don’t run on water. So you drain the tank and then find that the water has corroded the inside.
• Ethanol is 33% less energy dense than petrol, so you need more of it. A fuel containing 10% ethanol increases fuel consumption by 3%, though in reality that cost is offset by paying less for the fuel in the first place.
• A lot of ethanol is produced from corn and sugarcane, and land is required to produce it. In Brazil rainforests have been cleared to grow sugarcane to produce ethanol. And to grow it lots of fertilisers are used. However, and on the plus side, there is currently a lot of research into ways of getting ethanol out of wastepaper, crop stalks and crop waste, sawdust, and fast-growing grasses.
• When used in a two-stroke engine ethanol interferes with the fuel/oil lubrication and can damage the engine.
• Ethanol can corrode some plastic and fibreglass fuel tanks, and some old rubber and plastic parts such as fuel hoses and fuel tap and carburettor seals on older bikes, but these degrade anyway over time so it could be difficult to lay all the blame on ethanol. Fuel system components on newer bikes should all be able to cope with some ethanol, but many consider E10 fuel (10% ethanol) to be the limit.

Any reputable ethanol treatment has to address the issue of water absorption, and most products claim to do this, but not all of them do. And those that do tend to use alcohol as it is cheap. But hang on, ethanol is alcohol, alcohol is ethanol, they are the same thing, so how does that work? It doesn’t is the simple answer. And bear in mind that makers will try and hide the fact they use alcohol by calling it dimethylcarbinol or some other fancy chemical name, but anything ending in ‘ol’ is an alcohol.

So the solution to ethanol must lie in a formulation that does not contain alcohol and does not induce phase separation. Any product that claims to remove ethanol from fuel is definitely to be avoided, as none of them can do this. If you really wanted to reverse-engineer the fuel and remove the ethanol you can do so by adding water and waiting for the phase separation to occur, then drain off the water/ethanol mix, but then you would also be losing a lot of the octane from the fuel as well, so you would then have to use an octane booster additive.

But do we really need to worry about ethanol and use an additive to protect against it? Most of us don’t. But if you run an old bike with a fuel tank that does not seal well, and if you don’t use your bike much, especially over winter, and the tank is not kept full when the bike is stored, or if you have a two-stroke engine, maybe. Or you could just drain old fuel off and use fresh stuff after a layup.

Fuel degradation:

The issue of fuel degradation is probably of more concern than the use of ethanol. If fuel has been stored in the tank for a while it can degrade, and when it does it darkens. This is caused by polymerisation of its heavier-end components which then form gums and varnishes. If old fuel like this is burnt in the engine it will run but the heavier components won’t fully combust and will leave deposits. The best thing to do is to drain off old fuel and use fresh, but the use of stabilisers can prevent this happening in the first place, and detergents can clean off any such deposits that have already formed.

The fuel you buy at the petrol station already contains detergents that should help to keep a clean fuel system clean for a while, but they do not contain enough to maintain optimal performance for ever or to clean a dirty fuel system. Using fuels that do not contain enough detergents eventually leads to deposits in the injectors and on the valves, and these are the single biggest cause of a rough idle, hesitation and reduced performance, and increased fuel consumption.

How to combat the effects of ethanol and fuel degradation:

If you do feel the need to combat the effects of ethanol and degradation in fuel you need a fuel stabiliser, the purpose of which is to prevent phase separation and oxidisation. There is more than one additive that will do this, the most important thing is to make sure it doesn’t contain alcohol, as this will only make the problem worse. If the stabiliser contains a good product that will prevent phase separation then it is also acting to prevent corrosion in the tank, so whether you need an anti-corrosion additive in the stabiliser is a moot point. Many stabilisers also contain detergents that clean up the effects of degradation, again not a bad thing at all, and there are also dedicated fuel system cleaners, some of which work very well. Also look for antioxidants and dispersants as these treat the other processes of degradation that fuel goes through when stored. Avoid anything that claims to be able to restore fuel that has already had phase separation occur, as it can’t. Avoid additives that claim to do everything without mentioning specifics. Good additives to look for are PIB (polyisobutylene) and PEA (polyether amine).

One of the main questions is whether to use an additive regularly, or whether to do a single treatment every year or so. That really depends on what product you use and what dosage they recommend, and what the cost is, and whether your need is for prevention and maintenance or for cure. If you use the bike regularly throughout the year and run it on good fuel then an annual treatment using a good fuel system cleaner containing recognised detergents will more than suffice. If the bike sits around over winter or doesn’t get used much over the whole year, then more frequent use of a stabiliser may be advisable. If you know the bike is not going to get used over winter then fill the tank up and add a good stabiliser to keep the fuel fresh. If you have bought a second-hand bike with an unknown history then drain any old fuel and fill it up with fresh, and give it a good initial treatment to clean the system out.

Octane boosters:

The only time you should ever need to use an octane booster is if your bike is specified to use only 98 RON and all you can get is 95 RON, or less if you are outside the UK. Or if you are running a high compression sports engine for racing and you need to boost the fuel you are using because it is not good enough for the spec of the engine. The bottom line for road bikes is that you should use the fuel that the manufacturer recommends because that is what the bike’s combustion chamber, compression ratio, fuel system and ignition timing is designed and set up for. It is OK to use a fuel with a higher octane rating than that specified but really there is little point, as even though you might see a minor improvement in fuel consumption the extra cost of the fuel will offset that, and any performance increase will be hard to notice. The main benefit will be to the wallet of the fuel maker. But it is not fine to use a fuel with a lower rating than that specified to benefit your own wallet, as that will lead to detonation and knocking, and if that is allowed to continue, to destruction, and that will take out of your wallet a lot more than was left in it because you were trying to save pennies.

Conclusions:

Fuels are generally pretty good these days, but you do get what you pay for and using a good quality fuel does keep your fuel system cleaner and minimise the amount of ethanol used. An E5 fuel, that is one containing up to 5% ethanol, is not really anything to worry about. It is only when you get beyond that or the fuel is sitting around unused in a tank that does not seal very well that you need to think about using additives.

The three most common products you will see are fuel stabilisers that keep fuel fresher for longer and prevent the problems caused by ethanol, fuel system cleaners that clean a dirty system and keep it clean, and complete fuel system treatments that do both. Look for a product or products that contain antioxidants for keeping the fuel fresh, detergents for cleaning, and corrosion inhibitors for protection of all parts, including rubber and plastic ones.

The bottom line? Stay away from cheap fuel additives that seem to promise the world but only require small amounts to be used – you can guess the names and the stores they are sold in. Look for quality fuel additives that don’t have to rely on pie-in-the-sky promises to trick or confuse consumers, ones that fulfil a specific purpose using established chemistries and that know their limitations.

https://motorcyclepartswarehouse.co.uk/servicing/lubricants-fluids/fuel-oil-additives.html