Which oil is better - 5W30 or 5W40 in winter: what is the difference, deciphering the oil, which oil is thicker

ZIC X9 5W30

Characteristics:

• Price 4L – 1696 rubles.
• Flash – 224 °C.
• Freezing – -40 °C.
• Density at 15 °C – 850 kg/m3.

This is a high-quality synthetic composition, which is used even by those who love fast and extreme driving. Even negative temperatures will not be able to affect the functioning of the engine, the rubbing components of which are enveloped in a film that reduces wear. Thanks to this, the motor will last longer. The liquid does not evaporate and does not require topping up from replacement to replacement, which in modern cities is recommended to be done every 7000-8000 km. mileage

Pros:

• The best 5w30 synthetic motor oil can be used in turbocharged engines;
• The functioning of the power unit is improved;
• Ease of use due to the presence of a measuring scale on the package.

Minuses:

It is recommended to use high octane fuel. (function(w){function start(){w.removeEventListener(“YaMarketAffiliateLoad”,start);w.YaMarketAffiliate.createWidget({containerId:”marketWidget214″,type:”offers”,fallback:true,params:{clid: 2314538,vid:214,searchModelIds:,searchCount:6,themeId:10},rotate:{marketToBeru:false}});}w.YaMarketAffiliate?start():w.addEventListener(“YaMarketAffiliateLoad”,start);}) (window);

If you are looking for a good but inexpensive 5w30 motor oil that can protect against sludge, wear and oxidation, then this is an excellent choice that will last all year long.

General description of lubricants of this group

Motor oil 5w20 has many advantages over other lubricants, but the most significant advantage is the ability to increase the service life of the engine of various types of vehicles. Thanks to its unique composition, the oil easily cleans the power unit of carbon deposits and prevents friction from increasing, thereby increasing the efficiency of the engine. Once in the engine, the lubricant forms a durable oil film that is not damaged even under excessive load.

The product is based on a high-quality oil base, to which special additives are added, as well as individual elements (for example, paraffins), which give the product new, unusual properties. Often, oil marked 5w20 is suitable for diesel and gasoline engines, but this is not always the case. An additional advantage of the composition is that it has a very long service life and does not require frequent refilling. Oils are suitable for year-round use. The decoding of the oil indicates that the product has the following technical indicators:

We should also talk about deciphering 5W20 oil. All elements included in the code have their own meaning, or rather:

• “0w” - indicates that the lubricant is suitable for summer and winter. In the cold season, the lubricant will perform its functions at temperatures of -30.-35 degrees Celsius;
• “20” - the indicator indicates that the upper temperature threshold is only 20 degrees Celsius. This means that the lubricant is not suitable for use in hot climates.

Based on how this or that marking is deciphered, the driver can easily select the oil that will suit a particular car.

5W-30 or 5W-40 – which is better?

As I said above, these oils cannot be viewed from this point of view - this is better, and this is worse. We follow the recommendations of the engine manufacturer, what viscosity is indicated there, and pour it. Usually two numbers are indicated, between which you can choose a less viscous one for winter or a more viscous one, if there is such a need.

What else you need to understand, I repeat, SAE is not an exact standard and allows indicators to vary within established limits, this is especially noticeable in the example of low-temperature characteristics. Much depends on the composition of the oil. For example, 5W-40 synthetic may have a lower freezing threshold than oil from another manufacturer, made using a different technology, but with the same SAE viscosity.

In some cases, drivers increase the viscosity of the oil in order to reduce its consumption - this can be done, but as a temporary measure, in the end you still need to figure out what is the reason for the increased consumption, and mentally prepare to overhaul the engine if it has already completed its intended mileage resource.

A little about fakes

When choosing oil, we must not forget about fakes. Considering that oils whose manufacturers specialize in specific brands of cars are most often subject to counterfeiting, it would be a good idea to contact an official supplier in your city to select such a specific oil.

Most often, such oils are produced for expensive luxury cars, the oils for which have the highest requirements and are produced by companies such as GM.

You should also be wary of counterfeits for oils that are in high demand and have a complex chemical structure, which increases their cost and, accordingly, the number of counterfeits. For example, Liqui Molly brand oils should be chosen with extreme caution, giving preference to official representatives.

Differences between 5w30 and 5w40 - the main difference between them

• For type 5w30, the high-temperature viscosity characteristic is in the range of 9.3-12.6 mm²/s; 5w-30 oil is used in the temperature range from -30 to +35ºС.
• For oil labeled 5w40, the same indicator is within the range of 12.6-16.3 mm²/s; 5w-40 oil can be used at temperatures from -30 to +40ºС.

But we note that such characteristics are rather conditional. This means that the viscosity data declared by SAE and their relationship with air temperatures are very arbitrary and do not carry a practical load. That is, all characteristics are superficial, which must be taken into account during operation.

The difference in the characteristics of 5W30 and 5W40 oils is determined by the viscosity index at high temperatures. At elevated temperatures, grade 5W30 has higher fluidity and lower viscosity compared to 5w40 oil. This means that it creates a thinner protective film on engine parts than 5W40 oil, which is thicker. As the engine reaches operating temperature, 5W30 oil will be more liquid, and 5W-40 oil will be more viscous. At the same time, when starting the engine in winter, the oils behave absolutely the same and the difference between these oils is insignificant.

When comparing, the main difference between 5w30 and 5w40 is the difference in viscosity in the summer.

Only its manufacturer can say how suitable each brand of oil is for a particular engine. This depends on its type, design features, operational loads and other indicators.

It is better to pour thicker 5W40 oil into engines with large operating gaps, which will be covered by a thick protective film. It is used in internal combustion engines that operate at high speeds. This lubricant is recommended for engines operating in hot climates. Due to their lower high temperature fluidity, they create a thicker protective film that resists accelerated wear of parts and extends engine life. The 5W30 grade creates a thinner film, which leads to the threat of accelerated engine wear. But research shows that a thick oil film is not always a good thing.

User manuals describe the advantages and disadvantages of oils that form protective films of varying thicknesses depending on high temperature viscosity:

1. At an increased rate, the formed film is thicker than required by the operating clearances in the engine. This leads to the fact that it does not wash all structural elements well, since due to its high viscosity it does not spread over all components. As a result, these parts wear out very quickly, the power unit will begin to overheat, consume more fuel and fail. Therefore, if the manufacturer recommends filling with 5W30, there is no need to take risks using the 5W40 brand, even taking into account the fact that it increases the service period.
2. If the manufacturer recommends 5W40, the use of oil with a lower viscosity will lead to premature wear of the pistons, cylinders and other structural elements of the engine.

Article on the topic:

1. Toyota 5w-30 oil - characteristics and application
2. Engine oil 5w-40
3. Is it possible to mix synthetics with semi-synthetics?

Characteristics and distinctive features

The main difference between lubricating compounds 5W30, 5W40, 5W50 and 5W20 motor oil is that it is less viscous, that is, less thick in appearance. When used in an engine, 5W20 creates less friction due to a thinner oil film, resulting in less resistance between engine parts such as the crankshaft, valve train and pistons. This leads to a slight increase in the efficiency of fuel resource use.

This less viscous type of oil also allows the oil pump to move it from the sump to the rest of the engine more easily. This is what makes 5W20 preferable for very cold climates, where it is important to have a thinner oil consistency that allows the oil to flow easily when starting the engine.

However, in hot climates or in summer, less viscous oil is subject to thermal destruction processes.

The 5W20 marking is excellent for use in engines of foreign cars. For Russian cars, it is better to choose 5W40 oil, and it is also cheaper.

Gear oil viscosity according to API classification

Transmission oils, according to the API GL system, can belong to different classes. The division is based on the design features and operating conditions of the gears, as well as the content of anti-wear and extreme pressure additives (additives) in the composition. The following lubricant quality groups are distinguished:

• GL-1. This category of lubricant is applicable for gearboxes that are operated in light conditions. There are no additional additives in it, there is only a base. Sometimes they include some additives with antioxidant action, corrosion inhibitors, lightweight depressant additives and anti-foam additives. Such transmission oils are suitable for trucks and agricultural vehicles with spiral-bevel, worm gears, and mechanical gearboxes.
• GL-2. Category of liquids intended for use in moderate conditions. The composition includes anti-wear additives. Most often, these are used to lubricate worm-type transmissions in tractors and other agricultural machinery.
• GL-3. This category, suitable for moderate weather conditions, includes substances containing about 2.7% anti-wear additives. They are usually used to lubricate cone-type transmissions in trucks. The use of this product for lubrication of gears belonging to the hypoid type is excluded.
• GL-4. The category can be used in both light and heavy operating conditions. The substance contains effective extreme pressure additives (4.0%). Mainly used in transmissions, drive axle mechanisms in freight transport. Used on vehicles with bevel and hypoid gears, on trucks, heavy tractors, buses (commercial vehicles) with non-synchronized gearboxes. Suitable for final drives and other gears of most types of vehicles. Currently, gear oils of the GL-4 category are the main ones for vehicles with synchronized transmissions (this especially applies to European countries). If a GL-4 product is used, the label and data sheet must contain information about the intended use and information indicating compliance of the product with the manufacturer's requirements.
• GL-5. Products of this group are used for the most heavily loaded transmissions operating in severe operating weather conditions. The composition contains effective extreme pressure and multifunctional additives (about 6.5%). These lubricants are mainly used for hypoid gearboxes with a significant degree of axle displacement. They are universal and suitable for all mechanical transmission devices, with the exception of the gearbox itself. If the gearbox is a mechanical synchronized type, transmission lubricants with certified compliance with the manufacturer's requirements are used.
• GL-6. Such lubricants ensure normal functioning of the transmission under the most severe operating conditions. They have the ability to withstand rotation speed, increased torque, and shock load. They contain the largest number of anti-seize additives. However, GL-6 greases are rarely used. Most gear oils are mineral-based. Synthetic substances are practically not used.

In addition to the above types of lubricant, there are 2 additional categories that were developed in 1998. Employees of the American international community API, SAE and ASTM International (American Society for Testing and Materials), which deals with the standardization of products, worked on their creation.

These are the two classes:

• PG-1, or M-1, is used in non-synchronized manual transmissions in heavy vehicles. The composition is similar to the component content of GL-5 oils, with the exception of increased thermal stability;
• PG-2 is used to lubricate drive axles in heavy trucks and buses.

Classification

Today, different classification systems are used to determine which motor oil is best to pour into the engine.

Society of Automotive Engineers standard

Example of SAE oil

The most famous is the international standard SAE. According to this marking, the first and second numbers provide information about the viscosity of the motor oil at low and high temperature operating conditions, respectively.

The difference between these indicators gives an idea of ​​the temperature range in which the substance retains its declared characteristics. However, it does not provide complete data on all lubrication parameters.

American Petroleum Institute Standard

According to API specifications, automotive lubricants are divided into 3 groups.

1. S (Service) - created for power plants running on gasoline.
2. C (Commercial) - designed for diesel engines.
3. EC (Energy Conserving) – providing optimal operating conditions for a group of modern “engines” that require the use of energy-saving compounds.

Example of API compliant oil

To use this system to determine which oil is best to pour into the engine, you need to study the information on the back label of the container. If the marking looks like this:

• API CF is diesel oil;
• API SL/CF means dual-purpose lubricant.

Standard Association des Constracteurs Europeens des Automobiles

The European ACEA standard is close to its overseas counterpart. In this case, the letters indicate belonging to the class of cars and the type of their power units.

Example of an ACEA compliant oil

• A – passenger vehicles equipped with a diesel engine;
• B – passenger cars with a gasoline engine;
• C – commercial vehicles;
• E – heavy class trucks.

Standard International Lubricant Standardization and Approval Committee

Let us note that the International Committee for Approbation and Standardization of Lubricants has proposed its own system that allows the average person to independently determine which is the best oil for the engine of his car.

Example of ILSAC compliant oil

The IL SAC classification in practice turned out to be an attempt to introduce one universal standard that combines North American and Western European classification.

GOST and TU

Previously, in the Russian Federation, compliance of motor oil with GOST requirements was a prerequisite. Today, the state standard has given way to certain technical conditions that are practically not standardized, since each manufacturer determines its own parameters.

An example of oil that meets the GOST standard

Standardization according to GOST standards, from the point of view of the “Western tycoons” of a market economy, is a voluntary and unnecessary matter.

What does oil viscosity affect?

In a modern car, the performance properties of the oil are influenced by two key factors.

1. Possibility of cold start of the power plant in critical frost.
2. The strength of the protective film during overheating is sufficient to create the necessary lubricating layer.

Engineers, to please users and automakers, create lubricants with minimal low-temperature and maximum high-temperature viscosity.

Indirectly, correctly selected density affects fuel consumption, the duration of engine operation without the need for repairs, as well as its stable operation under overloads. The principle of operation can be clearly understood using the example of the new Lada Vesta crossover. A 5W30 type lubricant is poured here from the factory, functioning properly in the range from -25 to +30 °C. If the temperature outside falls below the limit, it will be difficult or impossible to start the internal combustion engine after being idle. Also, when used in racing modes, in a range above +35°C, the protective film will be destroyed (oil drains from the parts like water) and the effect of dry friction of surfaces will occur, which is fraught with negative consequences.

Requirements for winter oils

It’s worth starting the conversation with the operating conditions of the engine in winter. The fact is that low temperatures have a negative impact on the quality of motor lubricants. The substance thickens and cannot perform its functions in the engine. As a result, friction is provoked, and the engine can quickly become unusable.

Another negative consequence is the inability to start the engine at very low temperatures.

To avoid such problems, it is important that the oil for winter has the following characteristics:

• The minimum pumping temperature should not be lower than the severe frosts in which the car is used. This parameter is determined by the SAE index. Oils marked “5 W” meet the specified requirements;
• The minimum cranking temperature should not be less than - 30 degrees. The oils of the described group correspond.

Lubricants for 5W20 motor - meaning and temperature range

When I first encountered 5W20 oil, I realized that I was not dealing with an ordinary product, but with a substance suitable for a special environment of use. It was recommended to me by a friend who works at a service station. He said that he had already bought it and poured it into the car. Manufacturers promised buyers serious fuel savings and also guaranteed engine cleanliness. This actually turned out to be the case.

I later found out that many people pour 5W20 lubricant into the engine, only because there is no more suitable option. 5W20 motor oil from any manufacturer will be of high quality. Each company tries to improve lubrication and for this purpose uses special additives, additives, and cleans the oil base in certain ways.

As a result, the finished product can be safely poured into a car engine and watch how the car begins to work better. In my review, I will talk about what chemical composition the product has, how the markings are interpreted, and what cars the lubricant is intended for.

Rules for switching from 5W30 to 5W40

Converting a vehicle to fuels and lubricants with other characteristics may be necessary in various situations:

1. The maintenance period has come, and the used motor oil has disappeared from sale;
2. If the temperature range in which the vehicle is operated expands;
3. With prolonged use of the vehicle, wear on the engine's CPG increases. To improve performance, it is recommended to switch the engine to a more viscous oil.

Signals for the car owner about the need to change fuel and lubricants are deteriorating technical characteristics:

• Increased oil and fuel consumption;
• Reduced power.

But, it is important that the given parameters change within the limits specified by the car manufacturer in the operating manual or through official service representatives of the manufacturer. When the listed characteristics have deteriorated significantly, then the oil viscosity does not play a big role for the engine.

In such cases, it is necessary to diagnose the engine and identify the reasons for the decrease in performance.

When the listed characteristics have deteriorated significantly, the viscosity of the oil does not matter much for the engine. In such cases, it is necessary to diagnose the engine and identify the reasons for the decrease in performance.

In order to transfer a car from one synthetic to another, as when switching from 5W30 to 5W40, it is necessary to carry out a complete oil change procedure with mandatory flushing of the internal combustion engine.

additional characteristics

For any lubricant, in addition to viscosity, other properties are important, for example, detergent, anti-corrosion or even anti-wear. The viscosity of engine fluids is of primary importance. Additional additives increase the manufacturing cost and, accordingly, the market price of any product. Therefore, it is always necessary to pay due attention to all parameters and determine for yourself the optimal balance between all the functional characteristics of the lubricant and the conditions in which it will be used.

The main criterion for selecting lubricants for your car is the data set out in the operating instructions for a particular vehicle offered by its manufacturer. Typically, such documentation contains not only information about the necessary properties of lubricants, but also specific examples of products from well-known manufacturers are offered as an optimal option. If the car was bought a long time ago, and the instructions were lost over time, you can easily figure out the choice of engine oil yourself.

What does viscosity affect and decoding

The main task that engine oil must perform is to eliminate wear on engine parts by reducing friction between them. The reduction in friction occurs due to the film created by the oil between the rubbing parts. One part slides on an oil film relative to the other. This way the piston rings slide along the cylinder walls without scuffing, because a thin oil film remains on the cylinder walls.

But it's not that simple.

Fuel combustion in the cylinders occurs at high temperatures. Maintaining the operating temperature of the engine is carried out by washing the outer surface of the cylinders with coolant. Oil is a poor conductor of heat. Excessive amounts of it on the inner surface of the cylinder leads to overheating, loss of power and premature wear. And with low viscosity it does not impair heat transfer, but does not lubricate well.

In addition, at low temperatures, starting the engine is easier with oil of low viscosity, but after warming up, the viscosity becomes even lower, and the pressure in the lubrication system drops sharply. Adapting the lubricant to different operating conditions, manufacturers began to produce summer and winter types, for gasoline and diesel engines, for passenger cars and heavy equipment. Then all-season ones appeared as a compromise and an attempt to unify the application. At the beginning of the twentieth century, in order to streamline and clarify the labeling of oil and other petroleum products, the Society of American Automotive Engineers created a system of classification and characteristics, which is now called SAE.

To decipher such markings, you need to understand what each digital and letter index means.

• The first number indicates at what temperatures the fluidity of the lubricant disappears. The temperature taken as the starting point is 40 °C. From this temperature you need to subtract the first digit in the index, let’s say 10W, we get -30 °C. This means that the oil freezes when it cools to -30 °C.
• Designations with a combination of the first two characters, i.e. numbers and letters W indicate that the oil is winter. And the 10W combination is winter, freezing temperature is -30 ° C, cranking temperature is 25 ° C. (Subtract another 5 from the freezing temperature). That is, it is recommended for operation down to – 25 °C.
• Summer lubricants are designated only by a digital code - SAE 40, where the number 40 is the viscosity index at an internal combustion engine operating temperature of 100 °C.
• Designations with digital codes before and after the letter W indicate that the oil is all-season. So, lubricant with code 0W30 is recommended for use at temperatures from -35 to + 35°C.

Explanation and operating conditions of the 5W20 brand

Manufacturers use additives in automotive oils to improve the oil's performance when it comes to lubrication. Additionally, some other effects of additives in oils include cleaning engine deposits from engine parts, preventing corrosion or rust inside the engine, and preventing oil breakdown due to oxidation or extreme temperatures.

When we start our car on a cold winter day, we want the oil to be thin so it can instantly lubricate the internal parts.

Decoding 5W20 according to the SAE standard:

• The first number, 5, represents the oil's cold weather viscosity rating at 0ºC, where the letter "W" stands for Winter. Motor oil thickens when it cools and thins when it warms up. The lower the first number, the more resistant the oil is to thickening at low temperatures.
• 20 is the film thickness when starting the engine. On the other hand, the higher the second number, the more resistant the oil is to operating at high temperatures.

In production, a balance must be struck between the two, as oil that is too thick can cause fuel economy problems by requiring the fuel pump to work harder. Oil that is too thin will not be stable enough to provide sufficient lubrication between the moving parts of the engine.

Temperature Range

-35 ºC to +20 ºC

5W20 oil can be used all year round, in any season.

Technical characteristics of 5W-40 - decoding

The viscosity index has a direct effect on the temperature under which the lubricant can fully operate. For use in temperate climates, oils are often selected that can work in both summer and winter, and for cold regions they are suitable with a reduced viscosity.

5W-40 is a multi-grade oil that must maintain fluidity at negative and positive temperatures within specified limits in order to qualify for this SAE class. As I have said in other articles, SAE can be an indicator of the climate in which the oil can be used, only partially and only in relation to the low temperature indicator. In general, this is an indication of the viscosity of the oil at different temperatures.

SAE 5W-40 viscosity values ​​table:

From this table it is clearly seen that the second two symbols in marking 40 show what viscosity the oil will have at operating temperature, that is, it indicates the thickness of the oil film and how easily and quickly the oil will pass through the system

It is very important to select this indicator according to the manufacturer’s recommendations, since different engines have different design features

The first number 5 is an indication of low-temperature viscosity, that is, at -30℃ the oil will retain sufficient fluidity to crank the crankshaft.

According to GOST, the oil will be marked 3з/14. According to the API, it most often has a class SN, according to ACEA A1/B1 2010.

Let's sum it up

The easiest way to confirm the above is with a specific example. Or rather, by comparing the characteristics in the table. And it will immediately become clear:

Despite similar indicators, 5w30 and 5w40 are still different oils. And you can’t confuse brands.

Engine oil density at 15 degrees

Density is not often used when considering the technical parameters of an oil, but it is a fairly important parameter that determines how well the oil will create the required pressure, that is, how quickly and efficiently the liquid will reach all parts and provide them with reliable lubrication. The quality of heat removal by oil from parts and engine cooling also depends on density.

In fact, kinematic viscosity depends on density, that is, the kinematic viscosity itself is calculated using the value of dynamic viscosity and oil density. Since temperature affects density, for motor oil the measurement temperature for this parameter is 15 degrees.

Waste oil density

In general, the density of the oil determines the type of base and additive composition. The density of the oil is lower than the reference one - that is, the density of distilled water, since the lubricant contains large quantities of light impurities. With mileage, these impurities evaporate, and heavy ones, on the contrary, accumulate, which is why the density of the used oil will be higher than that of fresh oil. Measuring density is a good way to identify counterfeits. Some counterfeits are refined waste oils, but no matter how they are purified or supplemented with additives, the density will still not return to its original value.

How is density measured?

The density of motor oils is measured according to the general rules of physics - the ratio of weight to volume, that is, kg/m3. The density of the oil itself is not that important, unless you want to check the oil for counterfeit. More important is the preservation of this parameter, that is, fluidity, when temperatures change. The density of motor oils is measured at +15 degrees, while the temperature in the engine varies over a wide range from plus to minus during a cold start in winter

For this reason, when considering technical characteristics when evaluating oil, more attention is paid to dynamic and kinematic viscosity, which are essentially derivatives of the density value

Density value for synthetics and mineral water

By and large, the density of the oil depends on the type of base. Mineral oils are much thicker and therefore less stable at higher temperatures than synthetics. For mineral water, the density range is 875-856 kg/m3. For synthetics 840-860 kg/m3. But, as I said above, it is not the density itself that is important, but the preservation of fluidity at operating temperature, that is, kinematic viscosity.

Compatibility of 5w30 and 5w40 oils

There are situations when, in the event of a malfunction, it is necessary to urgently add oil to the engine. As a rule, the lubricant of the exact manufacturer whose product was originally poured into the engine is not always nearby.

The same applies to the oil viscosity index, and therefore you should know whether oils labeled 5w40 and 5w30 can be mixed. It is worth noting that it is often not recommended to mix oil with a fully synthetic mineral oil base oil. It is also not recommended to mix synthetics and semi-synthetics, etc.

As for lubricants marked 5W30/5W40, theoretically these liquids can be mixed with minimal risks only if they are both products from the same manufacturer. Mixing products from different manufacturers is allowed only in an emergency situation, but taking into account that they must have the same basic basis.

From this we can conclude that semi-synthetics are mixed only with semi-synthetics, mineral oil is mixed with a similar product, etc. However, it is impossible to answer unequivocally the question of whether it is possible to add a seemingly analogous 5w30 to an oil marked 5w40, since for For each type of lubricant, manufacturers use their own additive packages, which, after mixing, can react.

Even if there were no consequences in case of emergency topping up of liquids, this is an emergency measure that cannot be used constantly. After eliminating the breakdown, it is necessary to immediately drain the mixed lubricant from the engine and be sure to change the oil filter, and in some cases it may even be necessary to additionally flush the engine before changing the oil.

Is it possible to combine: different opinions

Motorists have been arguing for a long time about whether it is possible to mix synthetics with semi-synthetics. Some believe that varieties of oils were invented for a reason. They are convinced that mixing them will lead to negative consequences due to the radical difference in chemical formulas.

Experts believe that combining synthetics and semi-synthetics is better than synthetics with mineral oil

Others argue that this is just a marketing ploy. Since the base of synthetics and semi-synthetics is the same with minor differences, nothing terrible will happen. Only the additives may react, affecting the performance of the mixture, but the engine will not be damaged.

Experts believe that those who care about their cars should adhere to moderate views. Yes, you can mix different types of motor oil, but it is advisable to do this infrequently, use the same brands, and carefully mix formulations of different viscosity levels.

Oil from different manufacturers

Car enthusiasts know that products from the same manufacturer have the same chemical formula and set of additives with minor differences. Therefore, it will not conflict and will adequately serve until the next replacement. By the way, this fact applies not only to motor oils, but also to any branded products.

Motor fluids from different brands, but with API and ACEA standards indicated on them, also differ by category. For engines produced in 2000-2004, API SL mixtures are used. Motors from 2004 to 2009 respond to the API SM class without consequences. Modern machines accept SN and Low SAPS formulations without any problems. The latter are considered optimal, as they have an energy-saving formula that interacts ideally with exhaust gas neutralization systems.

Oil of different viscosity

Naturally, it is correct to use lubricants of the same viscosity so that the engine works properly. If this is not possible, it is better to use lubricants of different viscosity levels, but from the same manufacturer. It is designed to work together with minimal risk. You can drive it until the next replacement, but in the future it is better not to repeat this experience.

When adding oil of a different class, the overall viscosity will become worse - this is important to consider. If you mix products of different viscosity levels, the end result is lower quality

For example, when combining classes H and L, the result is H, even if L is added in larger quantities. This change affects the operation of the engine, since the fluidity of the substance decreases, making it more difficult to access engine parts.

If you mix products of different viscosity levels, the end result is lower quality. For example, when combining classes H and L, the result is H, even if L is added in larger quantities. This change affects the operation of the engine, since the fluidity of the substance decreases, making access to engine parts more difficult.

It is important to take care of the engine of your car, do not “feed” it with low-quality oil, otherwise it may fail

Determination methods and attached physical meaning

Today, several methods have been developed for automobile oils to determine all viscosity indicators provided for by the standard. All measurements are carried out using special devices - viscometers.

Depending on the value being studied, viscometers of various designs can be used. Let's consider several methods for determining viscosity and the practical meaning that lies in these values.

Cranking viscosity

The lubricant in the journals of the crankshaft and camshaft, as well as in the hinge joint of the piston and connecting rod, becomes very thick when the temperature drops. Thick oil has a high internal resistance to displacement of layers relative to each other.

When trying to start the engine in winter, the starter becomes noticeably tense. Thick lubricant resists turning the crankshaft and cannot form the so-called oil wedge in the main journals.

To simulate crankshaft cranking conditions, a CCS type rotary viscometer is used. The viscosity value obtained when measuring it for each parameter from the SAE table is limited and in practice means how capable the oil is of ensuring cold cranking of the crankshaft at a given ambient temperature.

Viscosity when pumping

Measured in a rotational viscometer type MRV. The oil pump is able to begin pumping lubricant into the system up to a certain thickening threshold. After this threshold, effective pumping of the lubricant and its pushing through the channels becomes difficult or completely paralyzed.

Here, the generally accepted maximum viscosity value is 60,000 mPa•s. With this indicator, free pumping of lubricant through the system and its delivery through channels to all rubbing units is guaranteed.

Kinematic viscosity

At a temperature of 100 °C it determines the properties of the oil in many components, since this temperature is relevant for most friction pairs during stable engine operation.

For example, kinematic viscosity at 100 °C affects the formation of the oil wedge, the lubrication and protective properties in the friction pairs pin / connecting rod bearing, crankshaft journal / liner, camshaft / beds and covers, etc.

Automated Capillary Viscometer and Kinematic Viscosity Viscometer AKV-202

It is this parameter of kinematic viscosity at 100 °C that receives the most attention. Today it is measured mainly by automated viscometers of various designs and using various techniques

Kinematic viscosity at 40 °C. Determines the thickness of the oil at 40 °C (that is, approximately at the time of summer start-up) and its ability to reliably protect engine parts. It is measured in a similar way to the previous paragraph.

Dynamic viscosity at 150 °C

The main purpose of this parameter is to understand how the oil behaves in the ring/cylinder friction pair. Under normal conditions, with a fully operational engine, this unit maintains approximately this temperature. It is measured on capillary viscometers of various designs.

That is, from all of the above, it becomes obvious that the parameters in the oil viscosity table according to SAE are complex, and there is no unambiguous interpretation of them (including regarding temperature limits of use). The boundaries indicated in the tables are conditional and depend on many factors.

What is the SAE classification?

This is a classification of motor oil by viscosity grade, introduced by the American Society of Automotive Engineers, which divides lubricants into separate subtypes according to their ability to operate at a certain temperature.

The viscosity of a lubricant is determined by the nature of the friction that occurs between the molecules of a given substance.

Several types of viscosity can be characterized:

• Kinematic viscosity is measured at two fixed temperature conditions, corresponding to 40 C° and 100 C°. The measurement occurs by recording the duration of the flow of a certain volume of liquid from a narrow vessel under pressure;
• The minimum temperature at which the oil pump can pump liquid is fixed.
• Dynamic viscosity is measured in mPa x sec. at a temperature of 150 C°.
• The minimum temperature at which the starter can be activated to turn the engine.

The SAE classification provides consumers with information about the temperature range of the operating environment in which the starter will perform its function efficiently and the oil pump will pump fluid through the entire system during a cold start.

According to SAE, oils are divided into 6 winter (0W, 5W, 10W, 15W, 20W and 25W) and five summer (20, 30, 40, 50 and 60) classes. The higher the coefficient, the higher, accordingly, the degree of viscosity of the liquid.

All-season oils, capable of performing the necessary functions in a wide temperature range, are marked with double markings that define the winter and summer classes, for example, 0W30 means that the lubricant must be poured into the engine with an operating temperature calculated from 0 C° to 30 C°.

The conclusion suggests itself is that 5W40 fluid is suitable for adding to oil with a viscosity class of SAE 5W30. It should be understood that it is not recommended to add 5W30 to 5W40 if the ambient temperature during vehicle operation is above 30 C°. In such cases, it is not recommended to mix the two types of lubricants mentioned. This can negatively affect the flow characteristics of the fluid.