Almost every car enthusiast has heard about various engine additives that change and improve the properties of engine oil, create a protective layer on parts, reduce friction and wear. As the manufacturers promise, after using such products, the engine becomes cleaner, the power increases, the noise decreases during engine operation, the reduction in friction ensures fuel savings, etc.
Note that among the most well-known and widespread compositions is molybdenum engine additive. Motor oils are also available for sale. various brands, which differ from analogues in that they immediately contain molybdenum. According to the manufacturers, this engine oil with molybdenum is a lubricating fluid that the best way protects the engine thanks to a balanced additive package combined with a molybdenum additive.
However, in practice, the warriors were divided into two camps. Some are completely satisfied with the additive with molybdenum and molybdenum oils, they note the stated advantages in the form of an increased resource, reduced noise during engine operation, etc. On the other hand, some car enthusiasts and experienced mechanics strongly do not recommend the use of such molybdenum oils and certain additives with molybdenum for a number of reasons.
In this article we will talk about how the molybdenum engine additive works, what benefits the use of such an additive provides, as well as what harm molybdenum can cause to the engine and in what cases.
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A little history
The protective properties of molybdenum disulfide (MoS2) have been known for a long time. Even during World War II, the Germans actively used this additive in oil on their equipment. This lubricant has especially caught on on tanks.
In case of damage tank engine and oil leaks power unit was able to continue working for some time thanks to the molybdenum protective layer. This often made it possible to leave the battle and get to the repair site on your own.
Also, the American military used oil with molybdenum in various units and components. For example, similar lubricants were used for helicopters during the Vietnam War. If an emergency oil leak occurred, the damaged unit continued to operate without oil, allowing the pilot to remain in the air and gain time to land the machine.
Molybdenum disulfide in the engine and oils with organic molybdenum
It would seem that the product has continuous advantages. However, after using oils and additives with molybdenum today, you can encounter both positive reviews, and with negative ones. Let's take a closer look at what this supplement is.
Let's start with the fact that molybdenum additives can be divided into two types:
- additives with molybdenum disulfide;
- organic molybdenum additives;
Molybdenum disulfide in the lubricant forms a special protective layer on the metal surfaces of parts that reduces friction. Numerous experiences and practical operation confirmed the unambiguous effectiveness of such an additive in various units (gearboxes, winches, etc.)
Let's move on. Taking into account the ever-increasing demands on oils, manufacturers are adding various anti-friction component packages to their products to increase the energy efficiency of lubricants and improve wear protection.
These additives can be liquid or solid and may contain esters, molybdenum additives, ceramic components or graphite. Molybdenum has long been a well-known extreme pressure and anti-wear additive in motor oil; it is similar in principle to graphite components and has a layered plate structure.
More precisely, molecular structure Molybdenum disulfide is a strong bond of 1 molybdenum atom with 2 sulfur atoms. Sulfur atoms are close in size to metal atoms. As a result, sulfur provides high adhesive properties, attaching to the surface of loaded parts.
So, the connection between sulfur and molybdenum molecules is strong, and the connection between sulfur molecules is weak. As a result, it turns out that the rubbing surfaces are actively coated protective layer from molybdenum molecules, while these molecules slide freely in relation to each other.
As a result, metal surfaces do not contact each other, friction and overheating are eliminated, and wear of parts is reduced. Also, molybdenum in the oil is stable, that is, it is constantly in suspension, without settling on surfaces. The molybdenum film that is still formed is characterized by its small thickness; it is not capable of reducing the design clearances in the engine and disrupting the free flow of oil to the loaded steam.
Now let us draw your attention to the fact that for engines internal combustion As a rule, the use of molybdenum disulfide is not recommended by the ICE manufacturers themselves or by experienced auto mechanics. The fact is that oil with molybdenum disulfide is a mixture, not a chemical solution.
In other words, such a lubricant contains solid particles of molybdenum disulfide, and the size of these particles is quite large. During engine operation, such particles end up not only on the surface of loaded rubbing parts, but also in areas where their presence can cause harm.
Grooves can also be noted as an example. As practice shows, oils with molybdenum disulfide under the influence of high temperatures in the engine contribute to rapid coking of the rings and their formation.
As a result, work is disrupted, gases from the combustion chamber break into the crankcase, the oil quickly ages and oxidizes, and engine coking intensifies. For this reason, it is better not to use lubricant with molybdenum disulfide or similar additives in the engine.
As for the alternative, among modern developments in the field of energy saving molybdenum oils With reduced viscosity(0W20, 0W30, etc.) you can find products using organic molybdenum. Specified antifriction additive is an effective friction modifier that is highly soluble in engine oil.
At the same time, the main protective properties are preserved. This allows the use of oils with low high-temperature viscosity without the risk of scoring and other defects on the surfaces of loaded parts.
In simple words, after reaching operating temperatures, low-viscosity lubricants become highly liquefied and form a thin oil film. Organic molybdenum in such lubricants helps avoid wear. The oils themselves with organic molybdenum differ from other products on the fuel and lubricants market due to their characteristic greenish tint.
Let us also add that today it is possible to reduce friction not only with molybdenum. As already mentioned, a similar effect is achieved through the use of synthetic ethers (esters). These elements also reliably “cling” to the surface, resulting in the formation of a thin and at the same time durable protective film.
Moreover, this film is very stable even under high heating conditions. As for the protective film itself after using molybdenum, the layer is not constantly formed. Once the film has formed, further formation occurs as the existing layer wears out.
However, this effect can only be achieved if oil with molybdenum is constantly in the engine. If you use a lubricant with molybdenum only periodically, then the protective film wears out, that is, you cannot talk about further maintaining the anti-friction and anti-wear properties.
Disadvantages of using motor oils with molybdenum in practice
As experts and experienced mechanics note, if previously it was possible to talk about any benefit, today the use of molybdenum is not justified in relation to the engine.
The fact is that previously motor oils did not contain an active package detergent additives. However, for last years the situation has changed a lot. Products last generations contain a lot of calcium, alkali, etc.
Simply put, calcium additives react with molybdenum, and this happens before the moment when molybdenum has time to create a protective film on the surface of metal parts.
The result of this reaction is a large molecule, and a cluster of such molecules settles on the oil filter, contaminating it. It turns out that it is undesirable to add molybdenum disulfide to modern oils. First of all, detergent additives in base oil react with the additive and are “triggered”, then the filter becomes dirty, and then the general contamination of the engine quickly progresses.
It is also worth adding that the use of lubricants with molybdenum in the engine requires special requirements for the interval regulatory replacement. In other words, it is better to change such oil as soon as possible. Moreover, if you “roll” on such a lubricant, then the consequences for the engine can be very serious.
The reason is that the oxidation products of molybdenum disulfide are molybdenum oxide and sulfur. Molybdenum oxide is abrasive and sulfur is corrosive. For example, we can consider a CV joint, where molybdenum lubricants are used quite actively.
A common situation is that a small crack appears in the CV boot and the CV joint quickly crunches. It is important to understand that through a small crack a large amount of dirt cannot enter the unit, but the element still fails. So, the breakdown occurs not because of dirt, but because air begins to enter through the crack.
As a result, molybdenum disulfide begins to decompose under the influence of oxygen. Moisture also penetrates through the torn boot, reacting with the sulfur in the composition of molybdenum disulfide and forming sulfuric acid.
It turns out that the acid corrodes the metal, and molybdenum oxide, which is similar to an abrasive, quickly wears out the part. It’s easy to guess that a similar situation can happen with an engine, and the cost of repairing it compared to the cost of replacing a CV joint is simply incomparable.
Let's sum it up
As you can see, although molybdenum disulfide is an excellent friction modifier and is capable of withstanding very large loads in friction units, pouring molybdenum into the engine is not recommended.
Also, some experts point out that in developed countries the production of oils with molybdenum is subject to additional tax. If we examine the approvals of car manufacturers, these additives have not passed the necessary licensing, since the indicators sulfate ash content after their use do not meet acceptable standards.
Taking into account the above, we can conclude that modern oils already contain a ready-made and fully balanced package of active anti-wear, detergent, extreme pressure, energy-saving and other additives. It turns out that in additional use There is no practical need for molybdenum for the engine.
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A car is no longer a luxury, but a means of transportation. Moreover, the range of these products is expanded from time to time with new products. Consequently, the auto parts market is also replenished with new parts and consumables, which include motor oil. The compositions of such oils play important role, since they have a direct impact on some components and assemblies of the car, allowing them to work as long as possible. The range of this product is quite wide and among all lubricants special attention oil with molybdenum is awarded.
There is a lot of controversy surrounding the product, which contains molybdenum disulfide. We, as outside observers, should find out what opponents base their suspicions on, and why oil attracts its admirers.
Two camps - supporters and opponents
The people were immediately divided into two camps. Some people don’t like it, others, on the contrary, praise it and almost sing odes to it. Typically, proponents rely on evidence from scientific research in laboratories. Opponents' conclusions are based on their sources, which are usually some “authoritative” auto shop consultant with limited knowledge, but with a great desire to sell something. They also attach importance to advice from an uneducated amateur mechanic.
I want to trust official institutions more in this regard. But let’s not get too far ahead and begin, so to speak, our investigation into what kind of product this oil with molybdenum is.
Molybdenum disulfide
First of all, it’s worth figuring out what kind of animal this is. The molybdenum disulfide molecule is a compound of one metal atom with two sulfur atoms - MoS 2. The silvery-black substance occurs naturally as the mineral molybdenite, which is the main ore for molybdenum. It is obtained using different methods:
- open method;
- side collapse method.
The compound has been known to people as a lubricant since the 16th century. Appearance MoS 2 resembles graphite, so molybdenum disulfide could not be distinguished from it until the 18th century.
The MoS 2 compound has a hexagonal crystal lattice and has excellent adhesion to metal surfaces. By polishing or spraying the material is applied to pistons, bearings, valves.
The use of molybdenum disulfide is relevant for systems that operate under conditions of low O 2 content. In addition, it can also be used for elevated temperatures with the inclusion of oxygen.
A little historical background
Any owner vehicle, no matter how much it costs, I always wondered what kind of oil would be better suited for his car. It is also important to know how often to change the lubricant. And in the process of choosing, I came across such a product as oil with molybdenum. Or perhaps no one has ever heard of this automotive product.
In fact, the MoS 2 compound has been used since the 50s, initially in aircraft construction. A liquid containing dispersion powder (a type of molybdenum disulfide) was added to the oil. The resulting lubricant was poured into aircraft engines of American military fighters.
This was done in order to preserve engine performance in case of crankcase breakdown and oil loss. In the event of such an emergency, the pilot had some time left to fly to the nearest airfield. All this is possible due to the unique lubricating properties of the additive.
Enterprising German
In 1955, an enterprising German citizen named Hans Henle bought the right to use the Liqui Moly brand and a patent for an additive using molybdenum disulfide. Before this, the lubricating fluid described above was sold under this name.
Two years later, a company called Liqui Moly GmbH was founded in the city of Ulm, and it was to it that oil with molybdenum owed its birth. From that moment on, the company began producing motor oil additives. At first, all products containing the MoS 2 compound were supplied to the market:
- Kfz-1 - for engine oil additives;
- Kfz-2 - for transmission oil additives;
- Kfz-3 - for the production of universal lubricant;
- Kfz-4 - for mounting pastes.
Currently, the company has a wide range of products supplied to automobile markets almost all countries of the world. Moreover, in Germany Liqui brand Moly was recognized as the best and received the “ Best Brand in the category of lubricants" according to many German magazines.
Unique properties
In addition to the automotive industry, molybdenite is also widely used in metallurgy in the production of alloy steels. Connection through our own chemical properties does not dissolve in liquid media. That's why Liqui specialists Moly molybdenum disulfide is introduced into engine oil using a special technology, which represents a real achievement of the company.
Molybdenum disulfide is ground into microparticles and then mixed with oil. However, they do not precipitate, but are always suspended. And then opponents would say that these particles will clog oil filters! However, this assumption is fundamentally incorrect, since the size of MoS 2 microparticles is much smaller than the through holes of any filter element. In this connection, the contact zone of the rubbing surfaces of the parts is always under reliable protection.
Its properties motor additive does not lose even with high rates temperature and pressure. In addition to the engine, other components of the car are also protected:
- main gearbox;
- transfer case;
- rear axle planetary mechanism;
- CV joints.
For planetary and gear transmissions, less typical extreme conditions work, the engine has many times more. However, these mechanisms also have their own characteristics - the so-called contact patch, where a lot of pressure is concentrated. Therefore, the use of oil with molybdenum disulfide in order to significantly reduce the coefficient of friction is more than justified.
Military purpose
The use of molybdenum disulfide in the early years was of a military nature. The fact is that during the Vietnam conflict the product was used to lubricate weapons. Thanks to molybdenum disulfide, the bullet passed easily inside the barrel and was less deformed. And its ballistic properties improved significantly, which had a beneficial effect on accuracy.
American pilots added molybdenum additives to helicopter transmissions. This made it possible, if damaged, not to immediately fall like a stone, but to fly to the base for repairs and to replenish ammunition.
Now the bullets themselves are coated with molybdenum disulfide during their production process.
Benefits of oils
The unique properties of the MoS 2 compound provide excellent properties to the produced motor oils containing molybdenum. Reviews confirm this once again. This is largely achieved due to the structure of the crystal lattice, which consists of sulfur and molybdenum atoms of equal size. The film between the rubbing surfaces is created so strong that neither high temperature (300-400°C) nor high pressure can destroy it.
The effectiveness of engine oil can be felt almost instantly after it is poured into the engine. Mechanical losses are reduced, which is reflected in a change in the tone of the power plant sound.
Currently, one of the suppliers to the automotive markets of many countries around the world is the already well-known Liqui Moly brand. Confirmed by the American Petroleum Institute high quality products manufactured by the company that comply high standards on energy saving - API EC.
This means that fuel savings can be up to 1.5% when driving the car moderately with a warm engine. In city traffic conditions and when the engine is first started, the percentage can be even higher.
How does the oil work?
A modern car contains components and assemblies that contain a considerable number of rubbing parts. For this reason, they need timely lubrication. And since the engine runs on fuel combustion, friction is accompanied by exposure to high temperature. The purpose of any lubricant is to reduce friction. Motor oil with molybdenum copes well with it, and reviews from many owners show how the car’s behavior has changed for the better.
Rubbing surfaces seem perfectly smooth only at first glance. In fact, they have a certain degree of roughness, it’s just measured in microscopic units. When motor oil touches rubbing surfaces, it creates a microscopic layer of film on their roughness, due to which friction is reduced. The thin layer is constantly renewed due to the continuous supply of lubricant under pressure. By the way, the potential competitor, Manol Molybdenum motor oil, has the same qualities.
And since the oil contains suspended solid particles, albeit very small in size, the meaning of everything is immediately clear. If all these microscopic irregularities and pores are covered with some kind of solid filler, the surface will become smoother. As a result, friction is reduced, which, in turn, leads to reduced wear of parts.
Public opinion
Majority experienced drivers and service station specialists note positive trends in the performance of motor oils with molybdenum additives. In particular, quiet and smooth engine operation. In addition, the quantity consumables remains unchanged throughout the entire period of use. Sometimes molybdenum in motor oil can lead to at least a slight increase in compression in the cylinders, which is officially registered.
Molibden Gasoline
However, worldwide famous manufacturer Liqui Moly is not the only one that produces high-quality motor oils. Recently, it is no longer possible to avoid worthy competition in the form of the Mannol oil concern. A product called Molibden Benzin 10W40 was released to consumers.
Semi-synthetic lubricant is made for gasoline engines. Characteristic feature can be considered a complete adaptation to urban road conditions in start-stop mode. The products have been tested and, in general, have proven themselves to be best side. As many people note, Molybdenum Gasoline is not inferior in its characteristics to Liqui Moly products. But this does not mean that it is superior to the previous product. After all, as other reviews show, Molybdenum Gasoline motor oil is not superior to its analogue in quality. In this they rely on equals.
There is one important caveat - the oil must be changed every 7,000 km. Otherwise, an oxidation reaction will inevitably occur, which negatively affects the performance of the engine.
Content Molybdenum disulfide powder
Today there are many both positive and negative reviews motorists about the use of special additives in motor oils that contain molybdenum disulfide. Let's try to understand what molybdenum additives in motor oil are and what function they perform when added to lubricants.
Today, requirements for engine manufacturers and lubricating oil formulators are becoming more stringent.
The use of friction modifiers, with the help of which anti-friction layers are created in areas of damage to the oil film, is one of the options for ensuring that motor oils have energy-saving qualities.
Molybdenum disulfide is a classic anti-wear and extreme pressure additive for lubricants and oils. All companies producing motor oils, in any case, include various anti-friction solid or liquid components in their products, such as esters, ceramics, molybdenum disulfide, graphite and others.
The principle of operation of these funds
Slightly soluble molybdenum additives in motor oil operate on a principle similar to graphite additives and are based on the lamellar layered structure of the additives. The molecules of molybdenum disulfide MoS2 include one molybdenum atom, with which two sulfur atoms are firmly bonded, the sizes of which can be compared with the sizes of metal atoms, which allows sulfur to be firmly attached to the metal surfaces of rubbing parts (pistons or bearings). The connection of molybdenum with sulfur is quite strong, while the connection of sulfur particles in nearby molecules is, on the contrary, weak.
As a result of adding molybdenum disulfide to the lubricant, both rubbing metal surfaces are coated with a protective layer consisting of molecules of this substance that slide freely in relation to each other.
This makes it possible to eliminate direct contact between metals and significantly reduce friction and overheating of parts in areas where it is present, especially in the case of extreme loads, which significantly reduces the wear of metal parts. Molybdenum additive
Stabilization of molybdenum disulfide occurs in motor oils quite well, which ensures the maintenance of a suspended state of the substance throughout its service life, preventing spontaneous deposition on the surface of engines, including hydraulic compensators. The protective film of this substance has a negligible thickness compared to the working gaps of the engine, which allows it to not maintain free circulation of oil. Does it happen machine oil with molybdenum? The answer is affirmative - such a substance is often present in modern lubricants. Molybdenum is a predominantly light-colored substance gray
, which often finds its main application in industry and metallurgy. The element has strong heat resistance and resists corrosion, and has good toughness. Such characteristics attracted the attention of car oil manufacturers to it, and it began to be widely used in lubricants. Probably, for people who are poorly versed in chemistry, this name will mean little, but motorists have to solve a dilemma that can be formulated as follows: should they use motor oil that contains molybdenum?
Oil with molybdenum has the widest composition of additives necessary for stable engine operation.
Brief description of the element Many modern automobile oils contain molybdenum disulfide compounds. Assessments of the effect of the product on the fuel processing system of a vehicle are completely opposite - from enthusiastic to very restrained and negative. The difference in estimates is explained by the fact that different brands
and models the substance is affected in different ways. It is still very difficult to determine which types of engines suffer from defects due to molybdenum and which do not.
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The way MoS2 works in motor oil is actually very similar to how graphite particles work. The molybdenum substance is based on a graphite plate platform. The compound contains one molybdenum atom and two sulfur atoms, which form a very strong bond. The sulfur-molybdenum compound is actually quite strong. The sizes of sulfur atoms are approximately the same as the sizes of metal atoms, which gives the combined mixture good protective functions. Moreover, without molybdenum such harmony would not have happened.
It is worth noting that the product has an anti-friction function. Today, almost all oil manufacturers add such antifriction compounds to their various products. These include graphite, esters, ceramics, etc.
and models the substance is affected in different ways. It is still very difficult to determine which types of engines suffer from defects due to molybdenum and which do not.
How does molybdenum affect?
Molybdenum has strong heat resistance and resists corrosion, and has good toughness.
So how does the product that interests motorists affect engine oil and the entire lubrication process? The molybdenum disulfide product was created to meet the highest manufacturing requirements technical details and the lubricants themselves. Among the benefits that the car owner receives along with the purchased product are very useful:
- The use of friction modifiers that help create anti-friction juices, the compounds of which, being in areas where the oil film is damaged, give the oil element energy-saving characteristics.
- Molybdenum disulfide has extreme pressure properties and prevents equipment wear.
- The use of special modifiers that stimulate friction creates conditions for the appearance of antifriction barriers in the area of oil film ruptures. All this gives them energy-saving properties.
- The process of friction and overheating of metal parts is reduced.
The sulfur molecules themselves form too weak a compound, therefore, when merging into the MoS2 compound, the two elements form a very powerful bond. When adding an element to lubricating fluid metal surfaces are simply covered with certain layers that have a protective function. Molecules move relatively quickly away from each other. As a result, direct contact of metal with other metal is eliminated.
The substance has a very small proportion in the lubricant. Considering the working clearances in the engine area, it cannot in any way disrupt the work process. Modern oil with molybdenum has the widest composition of additives. They allow molybdenum disulfide to create another lubricating layer. This layer comes into play when standard lubricant loses its operational properties. Molybdenum disulfide substance additives are today produced as a separate auto chemical product. These compounds can be added to specialized oil, improving its properties. Molybdenum elements can work where conventional lubrication does not work - during exposure to high or low temperatures. The compound of sulfur and molybdenum is capable of functioning at temperatures of 400 degrees Celsius. The additive is suitable for use in other extreme situations. A lubricant containing molybdenum disulfide is excellent for use in precision mechanics and as an additive for working in plastic materials.
and models the substance is affected in different ways. It is still very difficult to determine which types of engines suffer from defects due to molybdenum and which do not.
Skeptical assessments
Molybdenum elements can work where conventional lubricants cannot - when exposed to high or low temperatures.
To be as objective as possible, it should be noted that the product also has back side. It does not always appear, but some car enthusiasts are very reserved in their assessment of oil containing molybdenum disulfide:
- There is an opinion that molybdenum elements are better suited for large and very large propulsion units. For the powerful gasoline devices they are no good. After all, in fact, motor oil with the addition of molybdenum disulfide is not a standard combination of elements that enter into chemical reaction, but, on the contrary, a physical mixture. The particle sizes of the compound are very large; they fall not only into the necessary friction zones, but also where they should not, for example, in the area of piston rings.
- A lubricant containing molybdenum elements at fairly high temperatures increases coking or deposition of burnt products. This in turn leads to damage in the cylinder and piston area. This is almost always followed by a surge in the activity of gases entering the oil by penetrating through the piston ring area. All this inevitably entails thermal loads, technical issues and repairs. This fact largely explains why molybdenum disulfide is very cautiously recommended by some automobile concerns.
- Reducing the friction process is actually only possible with the use of a number of basic synthetic substances. We are talking about so-called esters, made from synthetic materials, very potent substances, which in their properties are almost identical to castor oil. They began to be used more often on racing units; they have adhesive properties and have a high thermal function. Skeptics believe that it is these synthetic additives that provide optimal friction, and not molybdenum sulfide.
- Modern oils contain too much calcium. Calcium enters into a very harsh and aggressive reaction with molybdenum disulfide, and before its elements settle on metal surfaces.
As a result, skeptics come to the conclusion that there are two most important reasons why molybdenum oil is not a very good choice today:
- The requirements for lubricant purity are too high. Molybdenum works well in lightly refined oil.
- The presence of calcium, an element too hostile to molybdenum disulfide.
If not for these two factors, molybdenum would still be an excellent lubricant additive today.
Having carefully assessed the positive and negative ratings of the product, all its pros and cons, the car enthusiast must decide for himself whether to purchase this product or not. After all, we are talking about the technical serviceability of the car. Molybdenum disulfide can serve both as a cause of defects and as a reliable protection for the vehicle’s fuel distribution system. It is believed that molybdenum disulfide molecules would be good to use today without the presence of various detergent additives. As an argument, the fact is given that in the 40s, during the Second World War, the product was used as a lubricant in tank units. If extreme oil leakage occurred, the engine could run for a certain period of time thanks to the molybdenum compounds. IN military equipment the oils had no detergent additives. From this, however, it is concluded that this is their strong drawback in their civil application where detergents are constantly used.
There are currently quite a few motor oils containing molybdenum on the market. Moreover, the amount of this component, its molecular structure and mechanism of action can differ quite significantly.
There is still ongoing debate on the Internet and among car enthusiasts about how justified the use of molybdenum in motor oil is. After all, lubricants containing this chemical element are often more expensive.
Let's try to figure out what molybdenum disulfide is in a lubricant - is it good or bad? We’ll also find out how this component helps lubricants protect the engine and whether it’s worth paying attention to oils with molybdenum-containing additives.
Brief history of the discovery
What is molybdenum? IN pure form it is a metal powder or lump metal of gray color with a low coefficient of friction and thermal expansion, high temperature melting and boiling.
However, in its pure form, this metal is of little value in the motor oil industry. Much more interesting are some of its compounds with other chemical components.
Molybdenum disulfide powder
The unique properties of molybdenum disulfide (MoS2) were known back in the mid-20th century. For the first time, documentary evidence of the actual use of this chemical element outside laboratory conditions relates to the military industry. In the 50s, Americans added molybdenum additives to oils used for tank and military aircraft engines.
It was noticed that if the engine lubrication system was damaged and there was an oil leak, the equipment could operate much longer “dry” until complete failure if there was molybdenum in the oil. This gave the tank a chance to leave the combat zone in time for repairs or for the plane to fly to the airfield.
Later, oils with molybdenum began to be used in civil engineering. One of highlights in the history of molybdenum-containing oils is the case with the founding of the Liqui Moly company.
In 1957, an enterprising German noticed a small bottle of strange liquid that was being sold in a part of Germany controlled by the Western Allies.
It was molybdenum disulfide, used in military aircraft. A German whose name was Hans Henle bought the rights to use this composition and began developing motor oils under the Liqui Moly brand.
Today, lubricants with MoS2 are not very uncommon. Molybdenum-based additives are used by many manufacturers of motor and transmission lubricants.
Moreover, technology has come a long way over the past few years. And these oils today are much more technologically advanced than they were before, and lack many of the disadvantages of the first versions of molybdenum-containing additives.
How does molybdenum disulfide work?
The MoS2 molecule, as is clear from the formula, consists of one molybdenum atom and two sulfur atoms. Easily combines into a film one molecule thick. Attracted to metal surfaces.
Crystal lattice of MoS2 film
Thanks to these qualities, molybdenum disulfide is quickly distributed over metal surfaces inside the engine and forms a thin surface layer. The film formed when the layers move relative to each other has a very low coefficient of friction. At the same time, the strength of the film itself and its adhesion to metal surfaces is very high.
In the event of shock loading or thermal decomposition, the damaged area is filled within a short time with free molecules of molybdenum disulfide located in the oil volume.
Advantages and disadvantages
Like any additive, molybdenum disulfide in its pure form has pros and cons. Let's first consider the advantages of using molybdenum additives in modern motor oils.
- Reduced friction coefficient in joints. This is one of the most significant properties that determine the popularity of motor oils with molybdenum. Low coefficient friction increases Engine efficiency, increases its power and throttle response, reduces fuel consumption.
- Increase protective properties rubbing surfaces. The protective film protects metal surfaces from dry friction during changes in mechanical loads.
- Rapid formation on metal surfaces and the ability to restore the integrity of the film in case of damage.
Effect of the amount of triatomic molybdenum on the friction coefficient
Today, oils containing molybdenum disulfide in their pure form are practically not produced. And there are several negative reasons for this.
- Molybdenum disulfide in its pure form begins to form molecular bonds even before contact with metal surfaces. This leads to the formation of coarse particles that have a density higher than that of the oil. If the engine is idle, molybdenum particles settle to the bottom of the sump and do not participate in operation for some time after the engine starts.
- After adding new oil, molybdenum forms a protective film on all metal surfaces. The remaining molecules circulate freely in the volume of the lubricating fluid. Being a compound that is not the most stable, molybdenum disulfide gradually decomposes into non-functional compounds and can no longer participate in the protection of engine parts.
- In some cases, excess molybdenum disulfide does not work for the benefit, but harms the engine. Manufacturers increase the concentration of this component in the oil to increase service life. Some molecules bind to metal surfaces into a film. The rest circulates through the system and settles in the form of clots in the most inconvenient places: in the gaps of piston rings, on sensors, in the bends of oil lines. Often these deposits lead to unpleasant problems.
Features of the operation of molybdenum additives in modern oils
Most modern motor oils do not use molybdenum disulfide in its pure form. The effectiveness of lubricants using additives based on pure MoS2 has shown to be ineffective and uncompetitive.
Modern oils are not considered in terms of individual modifiers used to improve performance properties. Additive manufacturers primarily make formulations that have comprehensive characteristics, and do not focus on individual components.
Under these conditions, the use of molybdenum required the development of new methods of delivery and implementation of this component. And such a solution was found in the use of a complex complex based on diatomic (Mo-DTC and Mo-DTP) and triatomic molybdenum organic components in conjunction with a zinc modifier (Zn-DTTP).
Molybdenum is added to oil in the form of a complex molecule that is quite resistant to destruction. However, under the influence of the zinc component, temperature and some other factors, complex molybdenum compounds gradually decompose to the familiar MoS2.
Moreover, this reaction over time is quite predictable and can be easily calculated.
It turns out that the addition of molybdenum dioxide is carried out in portions. This mechanism allows you to inject small portions of active molybdenum throughout the entire service life of the engine oil and fill gaps on exposed friction surfaces. This technology also minimizes the negative consequences of using molybdenum-containing oils.
Diatomic and triatomic molybdenum in interaction with zinc additives under a microscope
Therefore, today the use of modern molybdenum-containing lubricants manufactured using the latest technologies is more than justified. But before using them, you need to carefully read the car’s operating instructions. For some engine modifications the use of such oils is contraindicated.
Despite all the disadvantages, the advantages generally prevail. And today on the market you can find many brands of motor oils with molybdenum. Let us briefly consider not individual oils, but some manufacturing companies that use additives with this component.
A visual test of the performance of molybdenum in Mannol motor oil - video
- . Perhaps the most famous company using molybdenum-containing additives in its products. It was on this component that the entire marketing system was built at one time, which allowed the company to gain worldwide fame practically from scratch in a few years.
- Mannol. Inexpensive motor oils that use molybdenum.
- ExxonMobil. Uses molybdenum in some of its oils. In general, these lubricants are known for their innovative approach and search for new solutions.
- Idemitsu. In these lubricants Organic molybdenum compounds are used, which are the most stable.
To one degree or another, molybdenum-containing additives have been used by many motor oil manufacturers. Now this technology is in limbo. Many are actively developing and promoting it. Others, on the contrary, abandoned the prospect of using this component in their products.
