OIL ADDITIVES – DREAM OR NIGHTMARE? Mike Fishwick
Many of us have used oil additives over the years, our approval being based on the experience of others, and the long engine life which has been attributed to the claimed performance of these products, in spite of many manufacturers not approving their use. It has been virtually impossible to find any truly impartial source to qualify the claims of the manufacturers, and none of the vehicle manufacturers have been willing to clearly state the reasons for not approving their use.
The August 1992 issue of ‘Road Rider,’ an American motorcycle publication, did however publish a particularly interesting article on this subject, which in such a litigation-based country must be regarded as being both truthful and impartial. For this reason its findings must be regarded as being both significant and disturbing.
The author, Fred Rau, set out to collect all the reliable information available on the basic types of additive used in the USA, where the range is truly vast, over forty different products being identified during the first day of his research. In considering the properties of these additives he used only sources of information which were recognised authorities and were attributable, such as state universities, engine manufacturers, the DuPont Corporation, and NASA.
It was found that these additives could be divided into four groups, depending on their main ingredient – PTFE, zinc dialkydithiophosphate, standard oil additives in unusual proportions, and those composed of solvents and/or detergents. He did not, however, cover the use of graphite or molybdenum disulphide-based additives such used to be common in the UK (e.g. Acheson’s and Molyslip).
The most common additives in the USA, and probably this country also, are based on PTFE, or Polytetrafloeraethaline, sold as a powder suspended in engine oil, such as Slick 50. PTFE is usually sold under the name of ‘Teflon’ a registered trademark of the DuPont Chemical Corporation, who in 1982 clearly stated: “Teflon is not useful as an ingredient in oil additives or oils used for internal combustion engines.”
DuPont threatened legal action against any use of ‘Teflon’ in connection with oil products for internal combustion engines, and declined to sell their PTFE products for such applications. In the United States this predictably brought the lawyers scurrying from their holes, and as DuPont was unable to actually prove that PTFE was harmful to engines, they were forced to sell PTFE to the additive manufacturers. This situation still exists, but is not an endorsement of such use by DuPont, who remain somewhat aloof from the end product, and simply state that they have “No proof of the validity of the additive manufacturers’ claims.”
Some of the many small additive manufacturers in the US have obtained their PTFE from non-DuPont sources, with the result that the powder grains are of larger size than the original grade and may well obstruct filters or even settle out under gravity. Ever noticed that a certain manufacturer advises that the bottle of magic PTFE be shaken before use? It is interesting to note that the Southwest Research Institute of San Antonio, Texas, found that the addition of basic PTFE granules to lubricating oil increased wear rates. (See the Journal, April 1997 page 29.)
After a test of oil additives containing PTFE the NASA Lewis Research Center made a damning report that: “In the types of bearing surface contact we have looked at, we have seen no benefit. In some cases we have seen detrimental effect. The solids in the oil tend to accumulate at inlets and act as a dam, which simply blocks the oil from entering. Instead of helping, it is actually depriving parts of lubricant.” These effects would naturally be worse in the case of larger particles, which were incapable of being held in colloidal suspension where they will not settle out even under the centrifugal forces normally found in areas of a high-speed engine.
Besides being a friction-reducing medium, a basic property of PTFE is that it expands rapidly when exposed to heat. After a test carried out on the Petrolon Corporation the University of Utah Engineering Experiment Station found that: “There was a pressure drop across the oil filter resulting from possible clogging of small passageways.” In addition, oil analysis showed that iron contamination doubled after using the treatment, indicating that engine wear did not go down – it appeared to shoot up.
This test, carried out on behalf of the Petrolon Corporation (the original manufacturer of Slick 50), also found that after treatment friction was reduced by 13.3% while power increased by up to 8.1% and fuel consumption fell by up to 11.8%.
It should be noted that the Petrolon Corporation refrained from reporting the findings regarding filter clogging by their product, and also that in recent years the Slick 50 carton no longer carries its previous endorsements by Scania and the German TüV authority. It would seem that a definite question mark now hangs over the use of PTFE-based additives in engines.
Being a member of the fluroelastomer family, PTFE can be broken down under great heat (such as in an engine which is burning oil) and converted into hydrofluoric acid, an extreme corrosive which will, of course, eat through your exhaust system.
Another very popular additive is zinc, or to be exact, zinc dialklydithiophosphate, which is used a standard additive in many lubricating oils as an extreme pressure and anti-scuffing compound to reduce wear in areas such as the cam/follower and piston ring/bore. Its use became very popular during the ‘sixties in oils such as the original Castrol GTX, the proportion being increased in oils destined for the more arduous applications. This compound is also known to be a powerful eye irritant, causing severe and permanent damage.
As concern for the environmental effect of exhaust fumes and disposal of old lubricating oil began to grow, its use was reduced from anything up to 0.2% to today’s level of about 0.02%. Even at this low level it remains the main reason for the premature death of catalytic converters, as any zinc carried into the exhaust gas will combine with the catalyst and steadily ‘poison’ it.
Additional zinc, therefore, is now only available in the form of additives such as STP Engine Treatment. It should be remembered, however, that any additional zinc would only be of benefit in cases where the lubricating oil supply has broken down, and near metal-to-metal conditions exist. Excess zinc will not confer any advantage in normal operating conditions, and may promote spark plug fouling and deposit growth on exhaust valves.
Some additives, mainly available in the United States, contain a cocktail of additives similar to those normally used in engine oils, but in different proportions, and their use will naturally increase the overall level of the particular additives in your engine.
Many of the standard additives are termed as being synergetic, or able to act together, producing properties, which they could not exhibit individually. It is therefore possible that by changing the proportions of even one such additive the overall balance and operation of the additive package contained in the oil may be lost.
A good example is the addition of more viscosity improver, which in normal proportions will maintain the oil’s viscosity as it heats up. If used in excess this could produce an oil of such ‘improved’ viscosity that its flow rate is reduced.
The benefits – if any – of such additional additives are at least doubtful, but we are fortunate in that such additives are in the minority in this country.
Before the days of exotic chemical engineering, when lubricating oil technology was in its infancy, the main problem was that of sludge formation in bearings, oilways, and particularly filters. The use of anti-sludge additives was therefore quite common, which acted to dissolve deposits and suspend them in the oil, to be removed at an oil change or by consumption.
These additives did not use any exotic compounds, a good example being Wynn’s Friction Proofing Oil, which contained 83% kerosene! It is obvious that excessive use of such inflammatory solvents could result in dilution of the lubricating oil to the extent that its ability to prevent wear was greatly reduced, and the risk of a crankcase explosion caused by ignition of the kerosene vapour on an overheated bearing surface was increased.
Thankfully, this type of additive is now almost unknown, as good modern lubricating oils have adequate detergency properties to prevent sludge formation if changed at the recommended frequency.
A popular demonstration of the performance enhancement produced by oil additives has been to operate a treated engine without any oil. Most such tests use a stationary lawn mower-type of engine, which invariably performs without apparent distress. I remember reading of one such test where two oil-less cars lapped Silverstone at quite respectable speeds, the engine that had been treated with a molybdenum disulphide-based compound having no apparent problems, while the ‘Standard’ engine rapidly seized.
The Briggs and Stratton engine company carried out a similar test, running both the ‘Treated’ and ‘Standard’ engines for twenty hours before draining their oil, followed by a further twenty-hour run on both engines. After the second run both engines were stripped, it being found that while both engines had suffered from scored crankpin bearings, only the ‘Treated’ engine exhibited severe bore damage. Unfortunately the type of additive used was not reported.
Such tests can only be regarded as inconclusive, and a victory for the high standards of modern engine production, rather than a ringing endorsement for the ‘Miracle Additive’ of choice – unless followed up by a detailed stripdown report and a long-term test under normal conditions.
It is difficult to find a documented case on which to base a clear recommendation, but statements on oil additives from some reputable engine manufacturers and researchers give a clear lead.
Avco Lycoming, a major manufacturer of engines for light aircraft (including a rather pretty horizontally opposed range): “We have tried every additive we could find on the market, and they are all worthless.”
Briggs and Stratton, builders of some of the most neglected yet durable engines in the world: “They do not appear to offer any benefits.”
North Dakota State University, after conducting tests on oil additives: “The theory sounds good - the only problem is that the products simply don’t work.”
University of Nevada Desert Research Center: “Oil additives should not be used. The oil companies have gone to great lengths to develop an additive pack age that meets the vehicle’s requirements. If you add anything to this oil you may upset the balance and prevent the oil from performing to specification.”
NASA Lewis Research Center: “In the types of bearing surface contact we have looked at, we have seen no benefit. In some cases we have seen detrimental effect. The solids in the oil tend to accumulate at inlets and act as a dam, which simply blocks the oil from entering. Instead of helping, it is actually depriving parts of lubricant.”
University of Utah: “There was a pressure drop across the oil filter resulting from possible clogging of small passageways.”
DuPont Chemical Corporation: “Teflon is not useful as an ingredient in oil additives or oils used for internal combustion engines.”
While the Petrolon Corporation can certainly claim that: “Test results have shown that Slick 50 treated engines sustained 50 percent less wear than test engines run with premium motor oil alone,” Fred Rau found that these qualities were exhibited after a test duration of 100 to 200 hours. He also found that in cases where the test was continued for 400 to 500 hours the wear rates increased to at least those experienced before treatment (remember, that is only 25,000 miles at 50 mph!). He was unable to find a single researcher or engine manufacturer who would publicly endorse any oil additive.
There does no, however, seem to be any argument that the ultimate protection for your engine remains the use of a synthetic oil. It must however be remembered that at about £25 per oil change it represents very expensive overkill, unless you regularly use your motorcycle for long fast runs and extend the oil change interval accordingly. To use any synthetic in a K-Series is very expensive, as an oil change is obviously necessary when replacing the filter. Obviously, such a change would not satisfy the terms of any motorcycle manufacturer’s warranty.
Synthetic oils have their place, however, in machines such as the R45/65 and R80GS/ST, where the small 18 ampère-hour battery cannot provide reliable starting in extremely cold weather and a suitably thin mineral oil would not provide adequate protection under full load conditions. I have used Mobil 1 in my R45 for many years, using the little twin for long fast winter runs and changing the oil before every winter riding season.
Probably the best value for money in terms of engine protection is to treat it with sympathy, particularly while cold, and to change the oil regularly, particularly if your type of use involves a lot of short runs (i.e. under twenty miles). You do not need to spend a lot of money on oil, particularly if you buy it in bulk; an ideal lubricant for a K-Series or R850/1100 is Volkswagen 15-40 ‘SH’ graded oil, available from your local VW dealer in 25-litre drums at about £22. It is, however, a little thin for use in an ‘old’ twin, where I use B&Q 15-50 in my R100.
To sum up, the long-term case for additives remains unproven, with the only positive reports being either short-term or anecdotal in nature. It seems clear that while certain additives confer little or no useful advantages, others such as the better PTFE-based products can certainly satisfy the claims of their manufacturers in that friction is considerably reduced, so reducing fuel consumption and increasing power output. It is also apparent that in some cases these products could promote long-term problems in terms of accelerated wear, catalyst damage, fouling of plugs and exhaust valves, and exhaust system corrosion. Perhaps we are fortunate in not having access to the wide range of additives, which are available in the United States.
The decision on use of oil additives is up to the individual, but there appear to be compelling reasons to avoid their use and to spend the not-inconsiderable cost associated with them on more regular oil changes.
(The author would like to thank ‘Road Rider’ for the information on which this article is based, and member Julian Crompton for bringing it to notice)
Oil Additives - Previously published in the BMW Club Journal
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Mike Fishwick
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