Motor oils: oil properties, types, classification and characteristics

2024 Author: Erin Ralphs | [email protected]. Last modified: 2024-02-19 11:42

Beginner drivers face many questions when operating their first car. The main one is the choice of engine oil. It would seem that with today's product range on store shelves, there is nothing easier than choosing what the engine manufacturer recommends. But the number of questions about oils is not decreasing. Therefore, it is important for beginners to know everything about motor oils, oil properties, classification and technical specifications. After all, the wrong selection of lubricants for the engine can lead to disastrous consequences. Today we will consider this issue in detail.

Function

The elements of the power plant of any car are necessarily in interaction with each other. In the process of this interaction, friction arises between the component parts of the mechanisms. Due to the serious load of some parts and assemblies, the friction force between them can be quite high. To maximizeto reduce this force, and with it wear, lubricants are used.

Oil, in addition to reducing friction, also cools the parts, removing heat from the parts of the mechanisms. Another function is cleaning. The fluid washes away dirt and wear products from engine parts and assemblies.

Composition

Manufacturers produce several types of motor oils. The properties of oils are different and depend on the chemical composition of the product. Based on this criterion, all existing products can be divided into three huge categories. These are mineral, synthetic fuels and lubricants and semi-synthetic.

Any lubricant is based on a base oil and a set of additives. Characteristics, performance can be accurately determined only by the chemical composition of the base. Additives are needed to correct or improve properties. With the help of various groups of additives, the performance properties of motor oils can be significantly improved, even if they are not made from the best base. However, under conditions of long-term use, and especially at high engine loads, the additives break down and the final quality of the lubricating fluid that has worked in the engine for at least half of the period declared by the manufacturer can only be determined by the quality of the base.

The base can be mineral or synthetic. When combined, these two bases give a semi-synthetic base.

Motor oils are hydrocarbons with a certain amount of carbon. Carbon atoms are connected in straight and long, as well as inbranched chains. The straighter the chain of atoms, the higher the quality of the oil. For example, it is much easier for branched molecules to roll into a ball, since they are more compact than straight molecules. This is what the freezing process looks like. Branched atoms will freeze at higher temperatures than atoms in straight chains. But you need to get oil, which consists of straight chains of hydrocarbons, so that there are no impurities in it, there are no unsaturated bonds, rings.

Products derived directly from crude oil are brought to perfection through an advanced filtration process or less sophisticated methods. In mineral oils, the carbon chains are branched, but in hydrocracked oils they are straightened. However, in the latter case, it will not be possible to obtain selected molecules in this way. As for synthetic oil, it is made from volatile, light gases. The chain length is increased to the desired number of carbon atoms.

Mineral

They are made from base oil. The latter is produced directly from crude oil. In order to obtain a lubricant as a result, the raw material undergoes a filtration process using selective purification technology. Next, paraffins are removed from the resulting material. Mineral oils appeared among the first and were the first to be used for car engines. Today, the products of this group are rarely used. Why? In terms of performance, these oils are much inferior to products of the synthetic and semi-synthetic groups.

The chemical composition of the mineral base is very dependent on the quality of the basecrude oil, boiling point limits for oil fractions, technologies and degree of purification. The mineral base is the cheapest to manufacture. The product is obtained by direct distillation of oil, the molecules have different lengths and different structures. Due to this heterogeneity, the oil has unstable viscosity-temperature characteristics, high volatility. It is also worth noting the low resistance to oxidation. This is the most common motor oil base. Although the properties of oils are lower, due to the affordable cost, many manufacturers choose this particular base.

Mineral base products are amenable to improvement and improvement in two ways. The first direction is the purification of the base to such an extent that only the optimal amount of resins, nitrogen, sulfur compounds, and acids remain in the composition. Additionally, additive packages are introduced to improve functional characteristics. But alas, in this way you can not get a product of proper quality. The second direction is the purification of the base oil, in which any impurities are completely removed from the composition. Molecular modification is also performed using hydrocracking technology. The result is a mineral oil with a number of useful characteristics for heavy-duty, high-temperature operation.

Hydrocracking oils

In terms of cost, the products are very close to mineral oils. As for quality, sellers assure the consumer that the product has all the properties of synthetic motor oil. But an experienced car owner understands that if everything were so, then synthetic oils would cease to be produced forunnecessary. In fact, hydrocracking products are closer to “mineral water” not only in terms of cost, but also in terms of production technology. Oils are also made from crude oil. Why, then, is hydrocracking better than “mineral water” in terms of the chemical properties of motor oils?

The fact is that hydrocracking lubricating fluids undergo a deeper purification technology at the production stage. At the first stages, the technology is no different from the production of mineral oils. But then, using various physico-chemical methods, all unwanted elements are removed from the base. These are sulfur compounds, nitrogen, bituminous substances, aromatic compounds. Next, the paraffins are removed. But of course, getting rid of all impurities through hydrocracking is quite difficult. And this is the reason for the poor quality of mineral lubricating fluids.

It is interesting that most motor oils, which are positioned by the manufacturer as semi-synthetic and fully synthetic, are in fact ordinary hydrocracking oils. Products Shell, ZIC, partly Castrol, Mobil and others are all hydrocracking.

Semi-synthetics

This group is a blend of mineral and synthetic base stocks. The composition may contain up to 40% synthetic product. There are no requirements for manufacturers on the ratio of bases, just as there is no clear prescription for a specific synthetic component. The main properties of motor oils of this group are betweenmineral and synthetic. Characteristics are better than mineral water, but worse than synthetics.

Synthetic oils

Here, all products have exceptionally high quality characteristics in terms of viscosity and temperature. Here, the pour point is lower than that of mineral counterparts. The viscosity index is very high. This makes it easier to start the engine in winter. Also, the oil of this group is distinguished by a high degree of viscosity in the operating temperature range of the engine - the oil film will not collapse under thermal conditions.

We continue to consider the features of synthetic motor oils. The properties of oils are such that synthetics have a low tendency to form varnish deposits and soot. You can also highlight a small volatility and consumption "for waste". It is important that the minimum amount of anti-thickening additives is used in synthetics. Especially high-quality grades do not contain these additives at all.

All these basic properties of synthetic group motor oils reduce overall mechanical losses and wear of engine parts. But the price compared to "mineral water" is 5 or more times more expensive.

Additive packages

Even the best and most expensive synthetic oils are not able to maintain their characteristics for a long time when working in an engine. The reason for this is high loads, including high temperatures. We examined the types and properties of motor oils. Now we need to talk about additives, which form the properties.

Additives can be divided into three main groups - each is designed forspecific features:

The first and largest group is functional. This is a group that provides a huge number of positive characteristics. For example, due to these additives, the oil can have an increased anti-wear effect, and the antioxidant properties of motor oils increase. Due to the additives, foam is not formed, and engine parts are reliably protected from corrosion

The second group is the so-called viscosity additives. Viscosity, as you know, is one of the main characteristics of lubricating fluids. The function of these additives is to increase the viscosity index and then maintain it at a certain level, regardless of temperature conditions

• The third group is designed to increase turnover.

Classification

Consider the main classifications and properties of motor oil. Oils are usually classified according to the level of viscosity, as well as energy-saving properties. Different systems of classification and labeling are used. They are set by international standards. In the US, oils are classified according to SAE and API. European system - ACEA. In Russia, it is customary to distinguish products according to GOST 17479.1-85.

Russian classification

Depending on the level of viscosity, there are winter, summer, and all-weather lubricants. Oils are designated by a number and a letter. The letter “z” next to the number indicates that thickening additives are used. The larger the number in the marking, the higher the viscosity level. Depending on the engine and type of oil, the marking may containindices - 1 or 2. 1 is gasoline oil, 2 is diesel. If the letter in the designation is without an index, then this is a universal product.

SAE

In this edition, 6 types of oils are distinguished for winter and 5 for summer. Winter are designated by the letter W - 0W, 5W, 10W, 15W, 20W, 25W. For summer, they are marked with numbers - the higher the number, the more viscous the oil. The properties of motor oils, their marking in this version are more understandable even for a beginner.

API

According to the characteristics and operational properties of this system, products are designated as follows. S is for gasoline engines and C is for commercial diesel vehicles. The marking consists of two letters - the first indicates the category of the product. The second is about the level of performance. The farther the letter is located from the beginning of the Latin alphabet, the higher the quality of the liquid. For example, an oil grade marked SL is significantly higher than SJ. Universal lubricants have the index SG / CD, SJ / CF.

Conclusion

We examined engine oils, characteristics and properties, marking. With the help of this article, novice car owners will easily understand the features of lubricants. It is worth saying that sometimes you can deviate from the manufacturer's recommendations by choosing a higher or lower viscosity engine oil. But, as a rule, the plant can recommend products with different viscosities. Each driver chooses for himself the most optimal option based on climatic conditions. All-weather oil is considered 15W40.