Fuel and Oil Additives: The Need-To-Knows - Part Two

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 oil additives. Revisit out Blog page for the previous post on fuel additives.

 

 

Oil additives:

While some benefits can be gained from the correct use of fuel additives, the same can not necessarily be said of oil additives. In the days when oils were not as good as they are today it was a different story, but oils have improved remarkably since then while the additives have stayed the same, relying on marketing hype and scare tactics to keep them moving off the shelves.

 

There are three main types oil additive:

 

1          Those that contain friction modifiers.

2          Those that contain thickeners.

3          Those that contain detergents, dispersants and stabilisers.

 

Mostly they are sold under the first two guises, those with friction reducing properties that improve fuel consumption and increase engine life by reducing the friction associated with moving parts, and those with thickeners that restore and quieten worn engines and gearboxes. For the most part the marketing hype associated with those additives is nothing more than pseudoscience and psychobabble created by marketers to part well-intentioned bikers from their hard-earned cash.

 

And then there are the products that sell themselves as augmenters of the additives that already exist in the oil you buy off the shelf, those that act as detergents to keep your engine clean, dispersants that keep particulates suspended in the oil rather than on metal surfaces, and stabilisers or neutralisers that deal with acids that form in the engine.

 

1: Additives that contain friction modifiers:

Many of these additives contain PTFE (polytetrafluoroethylene, aka Teflon) or ZDDP (zinc dialkyldithiophosphate).

 

PTFE: The makers of additives containing PTFE claim that it will coat all your engine’s internals and reduce friction. However, when you think about it how are these magic molecules supposed to stick to the internal components if their friction coefficient makes them very slippery? DuPont, the makers of Teflon, thought the same thing, stating that “Teflon is not useful as an ingredient in oil destined for use in an internal combustion engine” and tried to refuse to sell it to additive makers, but lost a lawsuit and so had no choice. NASA research led to the same conclusion, saying that PTFE molecules do not bond to engine surfaces. What actually happens is that the PTFE molecules flow through the system along with the oil until it reaches the filter where it gets trapped and clogs it up, and this is compounded by the fact that a PTFE molecule expands as it gets hot.

 

ZDDP: This is a silicate-based lubricating compound developed in the 1940’s, and for a while it was considered the most effective metal-on-metal anti-wear additive available. Many oils already contain some ZDDP, as much as is good for modern engines and is allowed for environmental reasons, and it is for environmental reasons that there now exists a movement to ban it altogether, not so much because of the zinc content but because of the phosphorous. There is no doubt that for classics and old engines that sit around not being used very much ZDDP does have benefits, but too much ZDDP, especially in a modern engine, can be harmful as the oil can become too acidic, and can damage a catalytic converter. ZDDP works when it is activated by metal-to-metal contact, but under normal operating conditions most motorcycle engines have very little metal-to-metal contact, and so the ZDDP becomes a by-stander while the oil is doing its job of being the cushion between the bits of metal. Zinc on its own may be considered a better additive without the DDP, and all engine oils contain some zinc, enough for most engines. Too much zinc is associated with spark plug fouling and the formation of deposits on the valves.

 

One aspect of the use of friction-reducing additives in motorcycle engines is how it will affect the clutch, unless of course you have a bike with a dry clutch. Most have a wet clutch, that is it runs in oil, and for the clutch to work correctly you must use the correct oil or the clutch could slip. That is why car oils, which contain friction modifiers, should never be used in motorcycles. So if you are going to use a friction-reducing additive in your motorbike make sure it is designed specifically for bikes with wet clutches, and not for general use in cars.

 

2: Additives that contain thickeners:

These additives contain thickeners that the makers claim will reduce oil consumption, reduce engine noise, stop smoke, and repair leaks. And some of them may well achieve this, but by thickening the oil they are altering some of the properties that are essential for lubricating the engine correctly, particularly when starting it at low temperatures. All engines are designed to run on a particular grade of oil with particular viscosity characteristics, and as soon as you alter those characteristics your engine is no longer running on the oil it is designed for. There is a valid argument that if an oil is selected based on the tolerances and clearances when the engine is new, as the engine wears these clearances get slightly bigger and so a slightly thicker oil may be acceptable, but we are talking here about going from a 5W30 in a brand new engine to a 10W40 for the same engine with 100k miles on it. A thickening additive may increase the viscosity far beyond that.

 

3: Additives that contain detergents, dispersants and stabilisers:

The main question is whether these aftermarket additives are simply doing the same thing as the detergents, dispersants and stabilisers that the manufacturers put in when they make the oil. The longevity of oil has a lot to do with how long these additives last, and the better the quality of the oil you buy the less need there is for an aftermarket product to augment those additives. Engine makers specify a particular oil and a particular oil change interval that work hand-in-hand so the additives are still functioning when the change is done. If you use a cheaper oil the additives may not last so long so you should reduce the interval. And avoid the additives that state that you can extend the interval, because you really shouldn’t. And the cost of a cheap oil plus the cost of an additive is probably more than the cost of a quality oil.

 

A problem with these aftermarket additives is that they tend to concentrate more on the detergent than the dispersant and stabiliser, simply because it is a lot cheaper for them to do so. The detergents strip away sludge and carbon deposits from inside the oil bearing surfaces, which sounds like a good thing, particularly for older engines. But too much detergent can be harmful to the lubricating properties of the oil itself, in the same way as too much detergent can damage your skin. It strips away the essential boundary lubrication.

 

If your engine has been neglected and needs an extra clean it is better to use an engine flush treatment before draining the old oil. The detergents and dispersants a flush treatment contains will clean the engine and all the contaminants will be drained away with the old oil, and you are in no danger of compromising the qualities of the new oil by adding more of what it has already got enough of.

 

 

Conclusions:

Oils and engines are so good these days that as long as a high quality oil of the correct type and grade is used from the outset, and continues to be used, and the oil and filter are changed in accordance with the manufacturer’s schedule, the amount of wear will be minimal. So friction modifiers and thickeners should ideally never be needed in modern engines in the first place, and if they are used could be doing some harm. Generally they are a waste of money that should be spent on good quality oil and regular services. If however you are running a poor neglected old engine that is on its last legs and you can’t afford to restore it then give an additive a go and see what happens. If you do decide to buy an additive do your research on the products and make sure you choose one that suits the type, age and characteristics of the engine.

 

The bottom line? Stay away from oil additives that seem to promise the world. Good oil additives know their limitations and they know their chemistries. They don’t have to rely on pie-in-the-sky promises to trick or confuse consumers. So stay away from big claims on mileage improvement and power increase. Instead, look for additives that provide detergents and dispersants for cleaning and acid neutralizers for protection, but only if your current oil lacks them and your engine really needs them. And if you change your oil regularly and use a good quality oil that already contains enough of the necessary additives that will last to the next change, why bother with additives at all?

 

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