Winter operation of the car is a difficult test for the engine. And the right choice of engine oil often determines how smoothly and safely the winter period will pass for the engine.
In autumn, car enthusiasts often think about which oil is better in winter, 5W30 or 5W40? Some say that only the first part of the index, that is, 5W, is responsible for the winter qualities of the lubricant.
And since it is the same in both cases, there is no difference between lubricants. Others disagree and say that much depends on more than just SAE winter marking. And how things really are - we will understand below and in all the details.
Features of the engine in the winter
For a more complete understanding of the situation with the choice of winter oil, let's try to go from afar. That is, we will deal with the processes that occur in the engine during the winter operation of the car.
Pumping lubricant through the system with an oil pump
At the same time as the crankshaft is turned by the starter, the oil pump seeks to suck oil from the sump and drive it into the line.
The most heavily loaded and critical contact surfaces in the internal combustion engine are lubricated by force under pressure (main and connecting rod bearings, piston pins, camshaft beds).
And if the lubricant is too thick, then the pump may simply not create enough pressure to push the oil through narrow lines and spread it to all rubbing surfaces.
Under such conditions, the engine will not be able to work for a long time. The shaft journals and liners will receive critical damage before the engine warms up and the lubrication flow through the system returns to normal.
The work of an ultra-thin layer of lubricant in liners
If the oil hardens to a plastic state, then it loses its ability to create a so-called oil wedge and normally protect the engine necks.
When trying to start, it often happens that the crankshaft simply does not scroll. Many motorists mistakenly believe that the crankshaft counterweights (the so-called cheeks) get bogged down in the thick grease in the sump.
In fact, counterweights in modern engines do not touch the oil in the sump, in principle, never in a calm state, that is, at the time of start-up (if the level is not exceeded).
The cylinder walls are lubricated by oil mist in the crankcase and by supplying and spraying oil through channels in the connecting rods, as well as by picking it up with counterweights in motion.
It's all about the lubricant frozen to a plastic state between the liners and necks and, accordingly, an increase in resistance to cranking. For older engines, the situation is aggravated by the partial immersion of the cheeks in oil.
Temperature increase in gaps
Here, not only the fact of increasing the gap between the piston and the cylinder and the concomitant breakthrough of hot gases and liquid fuel into the crankcase plays a role, but also the resulting shock loads.
The piston no longer sits so tightly in the cylinder, bursting with compression rings, but dangles with a rather large amplitude by the standards of such precisely fitted parts. This will cause catastrophic wear if the cylinder walls are not lubricated in a timely and adequate manner.
In summer, these factors are minimal or non-existent. The engine is normally protected right from the start if the lubrication is good. Therefore, it is better to approach the choice of oil for the winter thoughtfully and with understanding.
Requirements for oils in winter
It was the features of the winter operation of the car that necessitated the creation of a system of special requirements for this period. Consider only the most basic parameters that are taken into account when assessing the winter qualities of engine oil.
These are the basic requirements tied specifically to the SAE viscosity index. It seems that theoretically there is no difference what to fill in the engine in winter: 5W30 or 5W40.
But in fact there is a difference. It consists in how much the manufacturer has improved the performance of lubrication relative to the nominal required by the standard.
After all, some oils lack a couple of percent to get the 0W index, while others barely made it to 5W. And in the first option, oil will be preferable for winter operation.
What is the difference between 5W30 or 5W40 oils for winter use
Many motorists mistakenly believe that only the winter part of the SAE index affects the performance of an oil in winter.
Why do they draw the wrong conclusion: pour into the engine in winter, if the temperature in the region allows, you can use any of the oils under consideration.
The so-called summer part of the index (actually indicating the operating viscosity at 100 ° C, which is approximately the same in summer and winter) also affects the performance of the lubricant in the cold season.
And here, first of all, you need to know the requirements of the automaker for oil. If the documentation for the car indicates that it is necessary to pour grease with an SAE 40 summer index, we pour this oil. If SAE 30 - accordingly, we select a lubricant with a viscosity of SAE 5W30.
There are some slight deviations from the rules here. If the motor already has a solid mileage, and you live in a region with amplitude fluctuations in annual temperature (it is cold in winter, hot in summer), it is better to take a thicker lubricant according to the summer index.
An example of the difference between 5w30 and 5w40 oil
That is, in winter it is better to pour SAE 5W40, as it may turn out that you have to drive for a long time with oil filled before winter. A thicker lubricant for a motor with wear, due to increased clearances in friction pairs, is preferable.
What oil parameters, besides viscosity, affect the operation of the engine in winter
In addition to the SAE viscosity index, engine oil has several more parameters that affect the nature of its work in the engine in winter.
- Viscosity index (VI). Shows how oil is affected by temperature fluctuations. Traditionally, the VI is higher for SAE 5W40 lubricants.
- Point of loss of fluidity. Not included directly in the SAE score. It is usually indicated on the back of the canister in a table with additional characteristics. Lubricants with a lower pour point will give more chances that the oil will remain fluid in severe frosts and allow the engine to start without problems.
- Base type and additives used. The better both the base and the more technologically advanced additives are used to create the oil, the greater the gap between the indices. For example, the vast majority of SAE 5W40 motor oils are synthetics. And 5W30 lubricants are often found in a semi-synthetic version. Synthetics are generally better for any mode of operation of the car.
| A good example of the difference in oils of one manufacturer | |||||
|---|---|---|---|---|---|
| brand | SAE class | Kinematic viscosity at 40/100 °C, mm2/s | Density at 15°C, kg/m3 | Temperature, °C | |
| Flashes in an open crucible | Freezing | ||||
| Shell Helix Ultra VX | 5W-30 | 73,1/11,9 | 848 | 200 | -39 |
| Shell Helix Ultra AB | 5W-30 | 64,7/11,4 | 848 | 204 | -42 |
| Shell Helix Ultra AG | 5W-30 | 69,5/11,7 | 854 | 230 | -36 |
| Shell Helix Ultra | 5W-40 | 72/13,1 | 853 | 206 | -48 |
| Shell Helix F | 5W-40 | 57,4/9,5 | 857 | 192 | -45 |
| Shell Helix Plus | 5W-40 | 82,9/14,8 | 850 | 230 | -36 |
| Shell Helix Diesel Ultra | 5W-40 | 79,5/13,9 | 854 | 228 | -48 |
| Shell Helix VA Diesel Plus | 5W-40 | 89,1/13,8 | 856 | 226 | -51 |
Summarizing
As is clear from the foregoing, the answer to the question of which oil is better to fill in for the winter, 5w30 or 5w40, is complex. We will briefly collect all the criteria that will help you make a choice.
Car manufacturer's requirements
Today, many automakers do not write only one suitable oil for all occasions, but give selection recommendations that provide for various operating conditions for a car.
If for your climatic region and with your level of engine load, the car manufacturer requires you to fill in 5W-30, you should not neglect its instructions.
If both options are allowed, then it is better to fill in a thicker oil. This may slightly increase fuel consumption due to increased viscous friction, but will have a much greater effect on improving the protective properties of the lubricant.
- Climate. For northern regions, where summer temperatures rarely exceed +20 ° C, you can safely pour 5W-30 grease if the manufacturer recommends it or allows two options for use.
- WITH motor wear rate. For engines with a mileage of more than 300 thousand km, even if this is not indicated in the operating instructions, it will not be a mistake to use a higher viscosity oil. That is, with the recommended SAE 5W30 class, you can fill in 5W40.
- Other oil characteristics. If there is any doubt about the choice, for example, for the middle lane, with a relatively new engine and permission from the automaker to use these two viscosity grades in the engine, other properties of the available engine oils should be considered.
Preference should be given to lubricants in which:
- higher viscosity index;
- below the pour point;
- a better base and a technological package of additives;
- there are other positive properties, such as energy saving or increased protection of contact spots.
In addition to the use of high-quality motor oils, the nature of the operation of the car greatly affects the engine life when driving in winter.
If you give the engine at least a minimum warm-up before starting to move, do not spin it cold to high speeds, change the oil and filters on time - there should be no problems after winter operation.
To service the car, you need to use engine oil. It is necessary for the good functioning of the engine, which subsequently allows you to increase its durability. Engine oil should be used all year round. Currently, there are three categories of motor vehicle lubricants: summer, winter and universal. and 5W40 are classified as universal types. This "all-season" makes them quite popular with motorists around the world. But many drivers think for a long time: which oil is better - 5w30 or 5w40?
Marking value
It is worth saying a few words about the purpose of marking. It allows you to characterize automotive lubricants according to the fairly common SAE classification. If two numbers are used in the marking of automotive lubricants, this means that these fluids are universal: they are suitable for use in both summer and winter.
Type 5w30
Marking on oils of this type means their characteristics. For example, the number five in this marking indicates the viscosity of the product during its winter use. The letter W, the designation of the English word "Winter" (which translates as "winter"), indicates the "all-weather" type of automotive lubricant. And the number "30" is the fluidity of the lubricant during the summer period of operation of the car. Since the marking indicates two numbers, this shows that 5W30 oils are universal and can be used both in summer and in winter.
The viscosity parameter in winter plays an important role. Under the influence of low temperatures, the lubricant of the power unit becomes thick. The thicker it is, the more the operation of the oil fluid pump located in the engine compartment of the car deteriorates. The number "5" indicates that the operation of this pump will be impossible at a temperature of -35 degrees.
The second number indicated in the marking shows that the viscosity of the lubricating fluid will reach a parameter in the range from 9.3 to 12.6 square millimeters per second.
Type 5w40
The main difference between the “40th” oil is that the parameter of the kinematic viscosity of the lubricating fluid will reach limits from 12.6 to 16.3 square millimeters per second. That is, less fluid during the summer period of operation of the vehicle.
Consequences for the motor that have arisen when using grease with an "incorrect" marking
When using a liquid with a higher viscosity, a thicker film layer is formed. Because of this, the lubricant will not flow to some mechanisms of the power unit, which will adversely affect the car's engine.
The likelihood of early wear and failure, as well as excessive heating of the engine, increases. This can occur if you fill in the "40th" liquid instead of the "30th".
If, on the contrary, much less lubricant will be spent on waste. However, the appearance of an oil film that is too thin contributes to the wear of the cylinder walls and piston wheels of the power unit.
The main purpose of using engine oil is to form a film that "lays" on all moving parts of the power unit. Small gaps that occur between the moving mechanisms of the motor require constant lubrication. After all, the occurrence of dry friction reduces the life of the motor.
Before using auto-lubrication, experts advise taking into account the model, age and conditions of use of the car.
How to choose the type of lubricant
What type of lubricant to choose: 5W30 or 5W40? Lubricating fluid 5W40 is a good option for use in the summer, with constant exposure to elevated temperatures. This type of lubricant “holds” the film quite well and does not allow dry friction to occur. "40th" lubricant is an ideal solution for engines that generate a huge amount of heat during operation.
Auto-lube type 5W30 is more fluid. This makes it easier to start the car engine in winter under the constant influence of sub-zero temperatures.
It is worth noting that when the operating temperature of the power unit reaches 120–140 degrees in it, the viscosity level of the lubricant for the 5W40 type is approximately one and a half times greater than that of the 5W30.
So, what type of automotive lubricant - 5W30 or 5W40 - should you use in winter? There is no particular difference.
Both types are universal and can perform their functions well both in summer and in winter.
But at the same time, it is worth noting that 5W30 is more fluid and is much less exposed to cold than the “40th” counterpart. These properties make it easier to start the vehicle's engine in the winter, under the influence of low temperatures.
Conclusion
Which oil is better 5W30 or 5W40 in winter? It would seem 5W30. But here it is impossible to answer unambiguously. It is worth paying attention to the model of the car, the period of its operation, the climate and, importantly, the recommendations of the manufacturer of a particular car model. And only after familiarizing yourself with all the parameters, you can fill one or another type of lubricating fluid into the engine of your vehicle.
Greetings, dear readers and subscribers! If you have a personal car, it means that from time to time there was a need to change the oil in the engine. Let's say you come to the store and want to buy an oil that can withstand both negative temperatures and summer heat. And here a dilemma may arise in front of you: what kind of lubricant to buy for the motor - 5w30 or 5w40? To answer this question, you will have to thoroughly understand the differences between these products and their characteristics. By the way, here are very useful articles on choosing oil for cars.
Choosing the right oil for your car means taking real care of the engine and thus ensuring its long-term operation without the need for early overhaul. This will serve as a certain guarantee that he will not present unexpected surprises at an unforeseen moment. But there are a huge number of varieties of lubricant on sale: they differ not only in the manufacturer or color of the canister, but also in. These and other criteria can be found on the container. But it is important to be able to read them correctly, because specific characteristics are hidden behind this.
So, it is in the parameters of each motor lubricant that the main differences between them lie, and, therefore, the scope. The designation of each of them contains an alphabetic and numeric part. It is they that display the degree of viscosity at both low and high temperatures, and these are the most important characteristics of motor lubricants. If the car will be operated in severe frosts, it should not be too viscous, otherwise it will make it difficult to start the engine. In the summer months, on the contrary, it should provide an oil film between the individual parts.
It is the letter W stands for winter which means "winter" in English. The first number in front of the letter is the criterion for the winter use of oil, and the second, respectively, for the summer. The presence of both numbers will indicate that the lubricant is all-weather. These data are approved by the standard SAE(this abbreviation stands for Association of Automotive Engineers). According to this standard, viscosity and temperature properties are decisive in determining the quality of the oil.
Main similarities and differences
Let's compare 5w30 and 5w40 automotive oils to conclude which one is better and more efficient for the operation of the power unit. In each of them there is directly an oil base, as well as a variety of additives, which produce the desired effect in the winter and summer seasons. The quality and quantity of these additives determine the viscosity grade of the lubricant.
These types of motor oil, which are compared in today's review, have different amounts of thickening additives in their composition. This directly affects the viscosity when operating at high ambient temperatures. Therefore, the next number (30 or 40 in this case) shows how long the oil is able to keep the protective film in the summer. Imagine situations where you stand in a traffic jam for a long time in city traffic during rush hour. A correctly selected number means that it will be possible to protect the motor from premature wear.
Thus, we have determined what is the difference between these two types of lubricant. Let's summarize it again:
- in the winter period of the year, both one and the other type of oil can be used at temperatures up to minus 25 ° C, that is, their properties will be identical;
- in the summer heat, 5w40 oil has a better degree of viscosity compared to 5w30, and this will directly affect the start-up and smooth operation of the power unit.
One could opt for 5w40 to get a more versatile solution for all occasions and any temperature. However, everything is not so simple. When choosing, it is also desirable to take into account the recommendations of the factory that manufactured your car. The fact is that the fluidity of the oil directly affects the operation of the motor as a whole, but much is also connected with its design features.
If the motor is designed for 5w-30, then filling in 5w-40 oil, we thereby increase the load on the oil pump and increase friction. This leads to a reduction in lubrication consumption in the oil system. This is explained simply - as soon as the hydraulic resistance increases, this leads to a decrease in oil consumption. The result will be engine oil starvation and accelerated wear. The reverse situation: if the manufacturer recommends 5w40, and you fill in 5w30, then the lubricant will turn out to be too liquid, and this will lead to the fact that the oil film will not hold well.
Of course, products with the 5w40 index are a more versatile option, but not for all cases. So, a lubricant with an index of 30 is more often recommended for new cars, and 40 or 50 for used vehicles. The average viscosity in a warm engine will be about 1.5 times that of 5w40 oil. It is also intended for operation in engines with high thermal stress. In addition, it retains excellent film and viscosity properties. This minimizes friction between metal parts.
What is dangerous?
What can threaten the use of an unsuitable and not recommended grade of oil? If its viscosity is greater than the required value, then the thickness of the film between the rubbing nodes under certain engine operating modes will be insufficient. It is clear that their accelerated wear is only a matter of time. Excessively fluid oil does not pose such a threat, since it easily fills all existing gaps. But there are also situations when the automaker allows the use of both types with certain reservations, depending on the operating conditions.
I really hope that today's review has lifted the veil of secrecy on the question of which engine oil to prefer. Therefore, I will be glad to meet with you in further materials. Bye!
Choosing the right oil is critical to optimal engine durability and performance. The motor needs adequate lubrication all the time. The oil maintains the optimum operating temperature, prevents wear and keeps parts clean.
According to experts, 0w-40 synthetic lubricant is optimal for the vast majority of European cars, and besides, it belongs to the category of all-season motor oils. In this article, we will compare the viscosities of 0w-40, 5w-40 and 5w-30.
Technical characteristics of oils 0w40 and 5w40
When it comes time to choose oil, a novice motorist can get confused as soon as he crosses the threshold of a car dealership or opens an online store page: the choice of lubricants is now very large.
The first thing to pay attention to is SAE oil viscosity, for example, take 0w40 and 5w40. It shows the performance of the oil at low and high temperatures. Choosing the right ratio of these ratios is important because a car engine has specific oil flow requirements for optimal performance.
Temperature range 0w-40:
- The letter W - means all-weather fluid.
- The number "0" is an indicator of winter viscosity, the oil does not lose its characteristics down to -35 ° C.
- The number "40" is the maximum allowable ambient temperature, up to +40 °C.
Difference between 0w-40 and 5w-40
The difference between 0w-40 and 5w-40 is small, but still there. The first version of fuel and lubricants is suitable for extremely low temperatures, as well as completely new engines, well, or with minimal mileage.
It should be noted that factories producing modern vehicles recommend using exactly “zero”, as 0W is called, in order to optimize fuel consumption and care for the environment.
Oils with a viscosity grade of SAE 5w-40 are multigrade oils, like 0w-40, but they differ slightly in terms of fluidity at minimum temperature. The temperature regime recommended for them is from -30 °C to +40 °C.
This option is most popular among motorists living in temperate European climates, where summer temperatures can reach high levels. In addition to this factor, 5w40 is suitable for engines with some wear, because due to its optimal density it remains in the engine, lubricating it during operation and at startup.
Comparative table of viscosity 0w-40, 5w-40 and 5w-30
Which oil is better for driving in winter: 0w-40 or 5w-40
Winter driving is one more stress for the car and its owner. You have to clear the snow, deal with the icing of windows and mirrors, and you also need to take care of the engine.
Automotive experts recommend that vehicle owners choosing 0w-40 or 5w-40 engine oil for the winter pay attention to vehicle storage conditions. We are talking about where the car "hibernates" - in the garage or in the open air. In the case of garage storage, the internal combustion engine does not experience any special problems during start-up, since it does not cool to an extremely low temperature, therefore, special requirements for viscosity are reduced to the manufacturer's recommendations.
The situation is a little more complicated for those owners who leave cars on the street. In this case, at the first start in the morning, the load on the engine increases very much, which affects the requirements for the choice of fuel and lubricants. Experts, in this case, advise choosing a more “liquid” option, for example, 0w-40, it will significantly reduce the risk of increased wear on the internal combustion engine at the time of launch.
Of course, few car owners will change fuel and lubricants before each season, but it is better to know the intricacies of selection in order to extend the life of the internal combustion engine.
Is it possible to mix 0w-40 and 5w-40
One of the most common questions that motorists ask is: is it possible to mix 0w-40 and 5w-40? And this is far from idle curiosity, as various unforeseen situations happen on the road. For example, the driver did not check the oil level before leaving and already on the track found that they had dropped to a critical level, and there was no canister to top up with him. He stops by the first store he comes across and finds that the product he needs, for example, 0w-40, is not there, but there is a similar SAE - 5w-40.
Automotive experts on this issue are unanimous, both options can be used for topping up without much harm. However, it is worth remembering that the mileage on such a mixture can be up to 3 thousand km. After that, it is necessary to change the oil to the one recommended by the manufacturer.
The only taboo in mixing oils is the combination of products from different brands. It is better to buy oil of the same brand, but with a slightly different viscosity and top it up, than to find one that is similar to the one filled in, but under a different brand.
Such a ban is due to the fact that motor oil manufacturers use different additives that do not always mix well with each other.
Comparison of technical features of oils 0w-40 and 5w-30
We have already thoroughly studied the features of the 0w-40 olive, so let's take a closer look at the 5w-30 and its features.
Synthetics 5w-30 refers to all-weather oils and has a temperature regime from -30 ° C to +25 ° C. The kinematic viscosity of this fuel and lubricant at an engine operating temperature of 100 ° C ranges from 9.3 to 12.6 units. The same indicator for 0w40 is 12.6-16.3. If we compare the kinematic viscosities of two oils, then the difference between them becomes obvious, so when choosing, you need to focus not only on the manufacturer's recommendations, but also on weather conditions and driving mode.
Fuels and lubricants 0w-40 and 5w-30 can be combined in one driving cycle between replacements, but, as we wrote above, it is important to use lubricants of the same brand and not exceed 3 thousand kilometers on such a mixture.
Automotive experts for winter driving, especially on high-speed internal combustion engines with low mileage, recommend using a more fluid oil, and this is 0w-40 in our case. This is also confirmed by the data on turning the engine parts at low temperatures: for 0w, this figure is 6,200 at -35 ° C, and for 5w - 6,600 at -30 ° C.
So if the car spends the night on the street in winter and is often operated at extremely low temperatures, it is better to give preference to 0w40 (provided that this does not contradict the vehicle's operating instructions).
The operation of any rubbing parts cannot be imagined without lubrication, the task of which is to reduce the wear of mating surfaces and remove heat from the friction zone. The internal combustion engine installed on most modern cars, like no other mechanism, is sensitive to the characteristics of the lubricants used for its normal functioning. This is due to the high speeds of rotation of the parts and the microscopic gaps between the parts. Plus, power plants are forced to operate in a wide range of temperatures, which, as you know, have a significant impact on the properties of materials, including lubricants.
International classification systems provide for the gradation of motor oils according to a number of indicators. The most important among them is the viscosity index, regulated by the SAE specification. Currently, one of the most popular are oils with the designations 5w-30 and 5w-40 defined by this standard. We have already familiarized ourselves in detail with the methods by which the viscosity-temperature properties of lubricants are established. The information given in that article will be needed to compare the characteristics of the oils in question.
Engine oils 5w30 and 5w40: difference in viscosity-temperature properties
So, the marking of oils 5w-30 and 5w-40 begins with the same 5w index, which indicates low-temperature viscosity, which affects the cold start of the engine and its operation at low temperatures. This parameter will not be of interest to us, since it is the same in both cases, which means that there are no differences in this part. But the second digit for the compared oils is different. It determines the high-temperature properties, characterized by two indicators - kinematic viscosity at 100 °C and dynamic viscosity at 150 °C. If we compare the values of these parameters for 5w30 and 5w40 oils, we will find that in the second case it will be greater, i.e. 5w-40 oil is more viscous. In practice, this means that the lubricant has a thicker consistency and, accordingly, less fluidity. In what cases will it be useful for the engine, and in what cases will it harm it? We'll figure out.
As you know, the gaps between friction pairs in the engine (for example, crankshaft-liners or piston-cylinder) are measured in thousandths of a millimeter (microns). The exact values are determined by the developers of the power unit. The resulting gaps must be filled with a lubricant so as to exclude the possibility of dry friction in some areas of the contact surfaces. What kind of oil is able to do this in an optimal way is known only by the engine manufacturer, as a rule, subjecting the assembled power units to a long series of tests. Lubricant recommendations can be found in the vehicle owner's manual. It is with this, and no other, data that the owner of the car must operate, choosing a specific brand of oil.
What can be fraught with the use of motor oils that do not meet the requirements? Everything will depend on whether the oil poured into the engine has a higher or lower viscosity than the recommended one. If an oil with a higher high-temperature viscosity is used, then at some engine operating modes the thickness of the film formed between the rubbing parts may not correspond to the required values. In the worst case, some areas may not receive lubricant at all for a short time. This is fraught with an increase in engine temperature and accelerated wear of parts. Conversely, using a lower viscosity oil does not pose such a threat, as it is more fluid and will therefore quickly fill the gaps. If we analyze our case, then if there are manufacturer's recommendations, it is impossible to use 5w30 oil exclusively. Castling back is possible, but undesirable, otherwise 5w-30 would also be on the allowed list.
Features of the seasonal use of oils 5w30 and 5w40
It happens that the manufacturer allows the use of any of the two types of motor oils under consideration, while often stipulating that it is preferable to use 5w-40 in conditions of high ambient temperatures. What are these recommendations based on? We have already noted that the designation 5w, which characterizes low-temperature viscosity, is responsible for winter operation. Since it is the same for both types of oils, there will be no differences in engine operation at low temperatures. But with a strong heating of the motor, certain features take place.
It is no secret to most motorists that the normal operating temperature of the engine is 86 ° C, and deviations from this value are minimal. Readings are taken from a sensor built into the cooling circuit of the power unit, i.e. engine temperature is nothing but coolant temperature. It would seem that the oil should not heat up more. However, in fact, the temperature of the engine oil under certain conditions can reach 150 ° C, and one of the factors affecting the maximum figure is the air temperature outside. So, driving in hot weather at low speeds (staying in traffic jams) definitely contributes to a more intense heating of engine oil than, for example, driving at medium speeds in cool weather. This is due to less active airflow around the power plant, which contributes to cooling. It is no coincidence that the SAE specification in terms of high temperature characteristics indicates viscosity values \u200b\u200bat 100 and 150 ° C. Thus, thick 5w-40 oil at higher ambient temperatures in a warm engine acquires a thinner consistency than if it were colder overboard. This allows it to form a film of the required thickness, which is taken into account by the manufacturer, who allows the use of this type of oil.
Use of 5w-30 and 5w-40 oils depending on the condition of the engine
During long-term operation of the car, wear of engine parts inevitably occurs, as a result of which the gaps between them increase. Accordingly, the thickness of the oil “layer” required for friction pairs also becomes larger. Up to a certain point, an increase in clearances does not affect the functioning of the power unit, but sooner or later the wear of parts becomes excessive, significantly exceeding the tolerances set by the manufacturer. In this situation, liquid oil, designed for completely different gaps, is not able to form a high-quality protective film in the interface zone of rubbing surfaces, which accelerates their degradation. Another problem may be the ingress of more oil into the combustion chamber and its increased consumption resulting from this. This is exactly the case when filling the engine with 5w-40 oil instead of 5w-30 is a justified step. Its thicker consistency will ensure normal lubrication, but it will not allow it to so easily seep through the increased clearances of the cylinder-piston group or gas distribution mechanism. Not without reason, after a certain mileage, many car dealers advise switching to oils with increased high-temperature viscosity.
Perhaps this is all we wanted to talk about in this article. We hope that the information presented will be useful in terms of a clearer understanding of the difference between the properties of 5w-30 and 5w-40 motor oils that affect the choice of one or another option in a particular situation.
