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The Truth About Fuel Additives


Is Diesel Snake Oil?

Some readers may recognize the term "Snake Oil" - the American slang given to medical products with dubious and unverifiable benefits in the late 1800s. Following years of questionable benefits, dubious recommendations, and wild claims, fuel additives are often viewed in the same manner.


I spent many years at sea, rising to Chief Engineer in the late 80’s. During that time, only very occasionally did I see lacquering on fuel pumps but never Diesel bug or lubricity problems. Diesel had not changed for decades and the engines were simple. Yet there were constant recommendations to dose with ‘fuel saving’ and ‘sludge busting’ additives, amongst others, at dose rates so small they would bemuse the best brains at NASA. Any additives required were put in by the suppliers, after all, margins and business were good.


Can diesel fuel additives improve engine power?


Have you heard the..."Increase power and get fuel saving up to 10%" - How? If it was that good, no one would have to sell it as owners would be beating a path to the supplier’s door. The reality has left few seeing any benefits and resulted in the belief that additives were deemed expensive and unnecessary.


Diesel is no longer made from easily sourced sweet crude...

Diesel Is No Longer Made From Easily Sourced Sweet Crude.

Fuel has changed completely: refiners are constantly under pressure to cut costs. They now refine 80% more from a barrel of crude than they did in the 1980’s, and these barrels originate from fields which were deemed uneconomical and of poor quality in the 90’s. As a result, today’s crude has more sulphur and undesirable elements. This poses greater challenges to the refiners, as they endeavour to supply a product to meet ever-increasing environmental legislation, and demands from the engine builders. All at a time when fuel margins have been squeezed to a minimum, business is not as good, and additives are a cost, so only the bare minimum is added to meet specification.


The Truth About Additives:


For decades there have been two additives readily available: one to apparently "save fuel consumption", and one to "kill Diesel bugs", as well as a multitude of suppliers who promised everything from both. The engine builders now make smaller, lighter, cleaner engines with massive leaps in technology, yet diesel fuel has been getting worse.

So now, finally, there is a need for well chosen additives that can play a very real part in the efficiency of modern diesel. By tackling lubricity, deposits, cold flow or cetane reduction, amongst others, additives can ensure the diesel is maintained, degradation gets slowed, and inevitable deposits from low sulphur diesel are prevented.


Did you know all the fuel manufacturers recommend a maximum life of 6 months for diesel? After all, they make diesel to burn, not to store for months or even years at a time...

Sludgy Filters and Deposits...

Diesel Bug Clogging a Fuel Filter.

If you have sludge in your filters then, yes, you need to look at your tank as you may have ‘Diesel Bug’. There are two types of diesel bug treatments: enzyme and biocides. Enzymes don’t kill the bugs, they remove their food; Biocides kill them, they act like the antibiotics we use when we have a disease. But what is the sludge from Diesel Bug? It could be asphaltenes that have agglomerated and fallen to the bottom as an oily tar like sludge, or it could be diesel oxidizing and degrading creating globules of dark sludge.


Stabilizers have a place and can help prevent oxidation, Dispersants can guard against asphaltenes, and Detergents protect the fuel components essential in modern common rail engines. A good additive package should contain only those chemicals required given the duty cycle of the engine and it's geographic position. Our DieselAid® LDB, for example, contains Lubricity, Detergent and a Biocide. It is formulated for fishing vessels and work boats operating in the ECA (see below) regions of Northern Europe. At 1 litre to 4000 litres of fuel, it is highly economic.

Manufacturers are encouraged - not always required - to treat fuel with stabilizers and lubricity improvers etc. Responsible ones do and some, not so responsible, don't. After all, additives are a cost to the manufacture so it's plain they will only put the very minimum in.

Asphaltene Sludge In Engine Component.

A word about water:


As discussed, additives have a place in modern diesel giving clear benefits. However, a lot of these benefits will be quickly reduced if water is allowed to build up. Water in the bottom of a diesel tank, is by far the single greatest contaminant you will find and will quickly lead to many problems.

Water and Diesel In a Glass.

Water accelerates the degradation of diesel: it forms a habitat for Diesel Bug; it reduces the lubricity in the fuel; it helps the agglomeration of asphaltenes; rusts the tanks and fuel system; and - in extreme cases - when absorbed in the fuel it can turn to super heated steam and blow the top off the fuel injectors!


Clearly then, water is not good but it is very easily removed by regularly opening the drain valve. For those tanks that don't have a drain valve, we recommend fitting a Diesel Dipper®. This smart bypass system sucks from the floor of the tank and allows water & sludge to be easily drained off.



ECA Zones...


If you bunker regularly in the Emission Controls Area’s (ECA), then a lubricity & deposit control additive should be used. Modern diesel in an ECA needs a lubricity additive which should be added by the supplier - most add the minimum, some don’t - adding your own ensures the fuel system is protected. Additionally, modern diesel causes greater system deposits referred to as IDID (Internal Diesel Injector Deposits). Modern common rail engines are highly susceptible to these deposits, and the only way to combat this is to add a detergent to the fuel.

Global ECA Zones.

Snake Oil is Still Out There Folks!


The claims still persist; however, during a recent exhibition I was presented with a product that would save 10% on fuel costs. To summarise: fuel additives will not improve your fuel consumption although a cetane improve may give marginal benefits. What they will do, is prevent the increase in fuel consumption from fouled fuel components, and certainly help prevent fuel system wear.

Contact us if we can help further or you have a particular fuel treatment requirement.



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