The arguments surrounding the subject of additives and their real-world efficacy has been raging for as long as additives have been on the market. Will a friction modifier lower engine wear or a fuel-system cleaner really make a noticeable difference to performance? The arguments pro and contra run almost entirely always along ideological dividing lines, based on deep-seated beliefs held on both sides of the debate.

It is easy to see why there is some scepticism, as gains are often not as pronounced as expected and not easy to demonstrate via simple tests, quite often relying on anecdotal evidence from personal testimony. Equally, those who use products year after year are also convinced that the benefits they report are more than just perceived gains. Add to that the solid science behind the products and it’s a recipe for conflict.

Conversely and unexpectedly, the answer is much more straightforward than you might think. Additives most definitely do work, which is easy enough to prove. All vehicle manufacturers specify them in their approved oils and lubricant manufacturers use different additive packages to blend their oils. The use of additives is conventional wisdom and modern engines and engine oils cannot do without them. You find additives in fuels to prevent waxing, stop engine knock etc, the list of applications is long.

The controversy arises around the debate as to whether individual products actually deliver what the manufacturers claim. The trouble being is that it is very hard to prove positive effects, like with benefits to health claimed by food producers.

No doubt eating a low-fat margarine will benefit your cardiovascular system over time by reducing your saturated fat intake, but a much more noticeable effect is gained from getting regular exercise. What is true for your diet is also true for additives, i.e., there are numerous factors that can affect the outcome of a treatment, which is why it is so difficult to obtain hard evidence of gains.

OILS

Additive packages in engine oils differ vastly according to the engine’s needs and motor manufacturer’s specifications. For example, antioxidants slow down the oil-aging process, this is why long-life oils contain higher amounts of antioxidants. But what if a long-life oil is either too expensive or simply not specified for the vehicle? This is precisely the situation where additives come into play and why the discussion around additives gets clouded by a lack of understanding as to what they can and what they cannot be used for.

Testing the efficacy of additives is often based on finding specific improvements which the additive cannot deliver. Most additives simply prevent wear or restore lost performance if the manufacturer has done a good job.

The advantages offered by modern engine oils with wear-reducing additives, such as tungsten particles, is often not available to older generation engines, because the respective oils are not based on that technology.

Here again, rather than buying an unsuitable modern engine oil, it often makes sense to use an additive containing a wear-reducing component. A one-shot additive is often the cheaper option in the long-run because one treatment lasts for several oil changes, not just until the oil is drained.

FUEL SYSTEM CLEANERS

Often it is claimed that additives are not necessary for vehicles driven in regions such as Europe or the USA etc, with a reliable supply of high-quality fuel and lubricants. However, even if a vehicle is maintained to a high standard and only high-quality fuels and lubricants are used, deposits still build up.

No air filter or oil filter can remove all of the contaminants contained in the medium it is filtering, which is one reason why residues form. Deposits accumulate over time, for example, as fuel decomposes, during the combustion process and many other reasons. Fuel system additives are designed to maintain a clean fuel system from the fuel tank to the combustion chamber.

One-shot cleaners are actually an effective and non-invasive method of removing deposits without the need to disassemble components or entire systems. Inlet valve stems are a recognised weakness, because they are susceptible to carbon build up, causing them to stick and not seal correctly, resulting in poor starting behaviour. The problem of sticking valves is especially pronounced under cold cranking conditions.

Fuel system cleaners can rectify this situation by breaking down heavy deposits, freeing the valve stems from carbon and allowing the valves to operate freely again.

From the maintenance perspective, it is only logical that additives are used at regular intervals to remove stubborn contamination from the fuel delivery systems and air-intake components. If the fuel system is not cleaned periodically, it can lead to increased fuel consumption, reduced power output and increased emissions.

Obviously, in the case of regions where high-quality additives are not contained in fuel to the same degree – or where tricks are used to increase the octane or cetane number of the fuel – is where aftermarket additives can make a significant difference.

FRICTION MODIFIERS

The principle behind adding friction modifiers to engine oils is to minimise power loss caused by friction losses in internal combustion engines. The loss of power can be traced back to contributory factors, such as viscous drag in the lubricant film separating the moving parts of the engine. Friction modifiers help to reduce the viscous drag whilst at the same time maintaining the crucial boundary lubricant film.

The role of the friction modifier here is to provide additives that are not contained in the engine oil. After adding the friction modifier, a molecule film is adsorbed by the metal surfaces in the engine, coating cylinders walls and piston rings. The layer covering the metal surfaces inside the engine, improves lubricant shear characteristics during relative motion. Lower friction results from the reduced film drag and can result in improved power and/or better fuel economy.

Premium quality oils often contain some friction modifying and anti-wear components as used in aftermarket additives. Standard oils, however, often do not contain the high-quality additives contained in the premium products, and this is the sort of scenario where a one-shot friction modifier comes into its own.

In effect, the whole dispute over efficacy and the quandary around the use of additives revolves around some additive producers making over-zealous claims about their products, often creating expectations that cannot be met. So, before you decide to purchase an additive, consider your options, i.e., the benefits you are looking for and whether you expect a massive performance boost or just to regain some of the performance lost over time.

One thing that you can be sure of is that an additive cannot reverse years of wear and tear. What additives often do well is to restore lost power, quieten a minor rumble, cure a minor leak or remove deposits.

What should you expect when you buy an additive? Realistic expectations are the order of the day. Do expect modest gains. Do not expect a new car with more power than it had when it left the factory.

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