"It is supposed to pour 5W-30 engine oil into the engine of my car, and I pour 5W-40, but I change it every 7-8 thousand km. Is this fraught with something for the engine?"
5W-30 and 5W-40 are the viscosity-temperature characteristics of oils according to SAE. In addition to this parameter, any oil also has performance characteristics according to API and ACEA. What they should be is also indicated in the operating instructions for the car. Depending on the model, for certain engines, tolerances according to factory specifications may also be indicated in the instructions.
What API and ACEA meets and what factory specifications the oil meets can be found on the label or label of any commercial container in which the product is offered for sale. In the example photo of the label, API and ACEA indices are visible, as well as compliance with the factory specifications of Volkswagen and Mercedes-Benz. If the filled 5W-40 oil meets the requirements of the API / ACEA index values in terms of performance and factory specifications, when they are stipulated, nothing should happen, except for the effect on engine operation of the difference in viscosity that this oil has compared to 5W oil -thirty.
There is no difference in low temperature viscosity (5W index here and there), but in a fully warmed up engine 5W-40 should be more viscous than 5W-30 (high temperature viscosity index 40 vs 30). In particular, according to the SAE J300 standard at 100 ° C, the kinematic viscosity of class 30 oils should be within the range from 9.3 to 12.5, class 40 - from 12.5 to 16.3 cSt. What could be the implications of such a difference? Let's reason together.
Obviously, at the same operating temperature of a normally warmed-up engine, more effort must be applied to pump a thicker liquid through the lubrication system. There is a prerequisite for increasing fuel consumption. In this case, the oil pump, which circulates the oil, and its drive must experience a higher load, which promises a reduction in their service life.
In addition, a thicker fluid provides greater hydraulic resistance to moving parts. This is another prerequisite for increasing fuel consumption. Again, after the piston rings have passed, the 5W-40 oil, being thicker, should leave a thicker film on the cylinder walls. Therefore, when operating on 5W-40 oil, one can also expect a slight increase in oil consumption for waste.
However, it is possible that these deteriorations will not be felt in reality. The difference of 3.5 cSt is very small. For example, at negative temperatures, the kinematic viscosity of motor oils reaches thousands of centistokes. It is this viscosity that actually affects the increase in fuel consumption in a cold engine, and this is known to any motorist.
The durability of the oil pump and its drive, given the margin of safety with which they are made, is also unlikely to be affected by the difference in high temperature viscosity between 5W-30 and 5W-40 oils. Much worse for them is dirty, oil that has not been replaced on time.
Besides, every medal has two sides. A thicker oil film is better for protecting piston rings, pistons and cylinder walls from increased wear at extremely high ambient temperatures, when due to insufficient cooling, which is possible for a variety of reasons, the engine is teetering on the verge of overheating. This situation is dangerous due to the appearance of breaks in the oil film and subsequent scuffing on the surfaces of rubbing parts. It is clear that the risk of too thin a film and breaks is higher for a thinner oil.
In plain bearings of the crankshaft and camshaft and other units lubricated under pressure, over time, due to wear, the gaps between the shaft journals and the liners increase. A thinner oil is more easily forced out of the gaps. If the gap is too large and the temperature is too high, there is a risk of premature destruction of the oil wedge and subsequent direct contact of the necks and liners, which is fraught with sticking them to each other, more intense wear and, in certain cases, even jamming and turning of the liners.
For these reasons, while being supporters of strict adherence to what is indicated in the operating instructions, we at the same time do not see much trouble from switching from 5W-30 viscosity oil to 5W-40 oil, especially when it comes to engines with mileage of 200 thousand .km and more. For them, it might even be better. The main thing, we repeat, is that the 5W-40 oil taken for replacement does not turn out to be worse in API and ACEA parameters than the instruction requires, and that the factory specification is taken into account, if it is specifically stipulated by the instruction. And, of course, when the engine is running, overheating is unacceptable, because any oil can be powerless against it.
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All drivers know how important a normal oil level is for engine operation. Sometimes there are situations when it is urgently necessary to add it to the engine, but there is no such lubricant at hand. Can I add another brand of engine oil? If you can interfere with them, then in what cases?
Basic classifiers of oils
To decide whether it is possible to mix motor lubricants, you need to be well versed in their classification. There are three main specifications by which you can determine the main characteristics of automotive oils. The viscosity-temperature properties are determined by the SAE International standard, created by the Society of Engineers of the American Automotive Industry. The next classifier that complements the quality characteristics of oils is API. It was developed by specialists from the Institute of Petroleum (USA). There is another standard developed by leading European automakers - ACEA. Recently, it has also become widespread.
SAE specification
Designations are always indicated on cans of engine oil - 5W30, 0W30, 5W40, 10W40 and so on. These are the coefficients of low-temperature and high-temperature viscosity, separated by the letter W. It is believed that the first digit means winter viscosity, and the last - summer. On this basis, the legend is accepted that oils are summer, winter and all-weather. In fact, no such division exists. Instead of "summer" and "winter", it should be understood - high-temperature and low-temperature viscosity. The very concept of "viscosity" implies fluidity, or internal friction between the molecules of a liquid composition. And these two figures are interrelated. If there is a designation SAE 20 or SAE 10W, this does not mean at all that the first lubricant works only in summer, and the other in winter.
For example, 5W30 means that the composition is less viscous than 5W40. The level of kinematic viscosity is usually measured at temperatures of 40 and 100°C. Dynamic viscosity is measured by heating the oil mixture to 150°C. According to this indicator, one can judge the density of the lubricating film formed on the surfaces of parts rubbing together. The higher this density (SAE 40–60), the greater the friction between engine parts. At the same time, with large gaps between the parts, the dense film will not break.
High viscosity lubricants are used for more worn motors when the gaps between parts are increased.
Low-temperature viscosity shows to what lower temperature limit the lubricant composition retains its working qualities and does not thicken. The oil pump will no longer be able to pump the thickened liquid through the channels of the system. In this case, we can talk about the relationship with the air temperature when a cold engine is started. If there is an inscription 0W on the canister, it means that the lubricant will retain its basic qualities up to a temperature of -35 ° C. The larger the first digit, the higher this threshold. For example, 5W only works down to -30°C. With the designations 5W30 or 5W40, the lubricant will work well at any temperature above -30 ° C, only the former will have a lower viscosity. That's where the term "all-weather" oils came from.
API classification
In this standard, all compositions are divided into 3 groups. Gasoline motor oil categories begin with the letter S. Diesel lubricants can be recognized by the first letter C. Energy-saving lubricants have an EU designation. Next in the designation is the second letter. The earlier categories are assigned letters located at the beginning of the alphabet - for example: SA, SB, SC.
All compositions for gasoline engines with designations from SA to SG are outdated today. Only SH (acts conditionally), SJ, SL, SM, SN are applied. The same applies to diesels - CF, CF-2, CF-4, CG-4, CH-4, CI-4, CJ-4 are valid. The earlier categories, from CA to CE, are now obsolete. SJ oil formulations are able to replace, in terms of their performance, all the earlier ones that were poured into old engines. Diesel lubricants, starting with CF-4, can replace CD and CE.
For new, modern gasoline engines, synthetic lubricants of classes SM, SN are used today. The SJ category is also common, many synthetic and semi-synthetic products correspond to it. There are quite a few universal oils on sale - for both types of engines. They are designated, for example, as follows: API SM / CF. The most stringent requirements for environmental and quality indicators correspond to oils of classes SN and CJ-4. The SN category was approved at the end of 2010, CJ-4 at the end of 2006.
ASEA
In this standard, lubricants are certified according to European testing methods. Europeans impose more stringent requirements on the quality of oils. The classification is divided into 4 groups.
Letters are followed by numbers. Now universal formulations are common. ACEA divides them into 4 categories: A1/B1, A3/B3, A3/B4, A5/B5. Sometimes the last two digits of the year in which such a classification was adopted are added at the end. For example, A1/B1-04. Oil formulations that meet the latest environmental and quality requirements - A5 / B5, C4 and E7. The most common today are oils of categories A3 / B4. According to the ACEA standard, the requirements for A5 and B5 formulations are more stringent than for liquids of the best API classes - SN and CJ-4.
Mixing rules for the composition of oils
In addition to the characteristics, the composition of the oil mixtures should be taken into account. Modern lubricants for automotive engines have two main components - a base oil and an additive package. The basic base occupies from 80% of the volume and above. Additives can take up to 20% of the total amount in the mixture. The base composition can be mineral, semi-synthetic or synthetic. Additive packages may also differ, but only slightly.
Although each manufacturer has its own preferences, oil blend additive packages do not conflict with each other. Therefore, oily liquids can be mixed without paying much attention to additives.
Basics
Will the base lineups clash? There will be no obvious contradiction in the form of some kind of chemical reaction. But if, for example, a mineral base is poured into synthetics, the overall quality of the lubricant will noticeably deteriorate. The mineral base composition has a lower viscosity index (not to be confused with SAE viscosity).
This index expresses the ability of lubricants to maintain their viscosity properties in a certain temperature range. The higher it is, the better the oil mixture works. This is important for modern turbocharged, high-speed engines. There, the lubricant must work at very high temperatures. Under these conditions, it is dangerous to mix mineral water with synthetics - the mineral base will quickly lose all its working qualities.
Synthetic bases may also differ. The hydrocracking method is used to purify oil fractions to the maximum, while obtaining compositions of a high degree of purification. Their performance is very close to real synthetic bases. Therefore, lubricants based on such substances are sold as synthetic. Although in reality they are not.
Additives
With additives, the situation is easier. They improve certain properties of base oils. Today, the following additives are mainly added:
- anti-wear - increase the service life of parts between the rubbing surfaces of which an oil film cannot form (for example, too small a gap);
- detergents - wash out all kinds of deposits and soot, according to the principle of action they are divided into detergents and dispersants;
- antioxidant - prevent the oxidation of oil mixtures;
- anti-corrosion - prevent corrosion of metal surfaces from oxidation;
- friction modifiers - reduce the overall coefficient of friction in a running motor;
- antifoam - do not allow the formation of foam in the oil when it is shaken by the crankshaft in the crankcase.
You can mix motor oil with similar characteristics from different manufacturers - the additive packages in most products have a similar composition and will not interfere with each other. But this is not a rule, but a short-term exception in case of a hopeless situation!
Viscosity
Why are low-viscosity oil mixtures used in modern engines? Because they perform the dual role of classic lubrication and hydraulic fluid. For example, Honda's VTEC systems or CVTs are controlled by engine oil pressure. In addition, low-viscosity lubricants are able to create the required pressure in narrow channels and flush parts in hard-to-reach places.
In the presence of such features, mixing 5W30 grease by adding a more viscous 5W40 is not recommended, it will only interfere with normal operation. Even if both fluids are from the same manufacturer. But there will be no dangerous consequences for 500-1000 km of run.
If:
- you can safely ride until the next change of motor fluid.
Lubricants for diesel and gasoline engines
It is worth dwelling separately on a mixture of oils intended for gasoline and diesel engines. What is the difference between them? These motors have different operating temperatures in the piston groups. Diesel is hotter due to the high pressure in the combustion chambers. Therefore, diesel lubricating mixtures are oriented to a higher temperature, their viscosity index is higher. Detergent, anti-friction and other properties are also at their best. For example, diesel fuel leaves a lot of soot, which must be constantly washed off.
Diesel lubricants can be added to a gasoline engine. Especially if the viscosities match. On the other hand, it is strongly discouraged. Even universal lubricants are mainly intended for older diesel engines ( API – CF), so you have to be careful here.
conclusions
There are a lot of videos on the Internet where the authors claim that you can mix anything, in any proportions and viscosities - be it 5W30, 5W40 or 5W60, mineral water or synthetics. Actually this is not true. You can mix oily liquids only in the most extreme cases, when there is no other way out. For example, during a trip, a leak appeared, and the motor gradually loses lubrication. The goal is to use any other oil composition so that you can drive a couple of hundred kilometers to the service station. There, find the cause of the leak, flush the engine and fill in the oil that is required. Such a run will not interfere with the motor, it will not have time to be damaged.
You can mix synthetics with synthetics, mineral water with mineral water, add synthetics or mineral water to semi-synthetics, since both bases are already there. All this is permissible if lubricants from the same manufacturer are mixed - even if they belong to different model series, but have similar characteristics and the same basic composition.
The extended temperature range of 5W30 and 5W40 oils has made them popular with Russian car owners. Why? What benefit will the engine get from this, which oil is better: 5W30 or 5W40 in winter?
Synthetics or semi-synthetics
There is currently a trend towards a wider range of viscosities. Chemists have made the most significant steps in this direction in relation to the creation of synthetics, adding more and more new components there. For example, Mobil, which was the first to bring a synthetic lubricant to the market, has been working with it and experimenting for over thirty years. A huge number of emerging competitors are also on the alert and spend huge amounts of money to create a new product with advanced features. But there are few developers producing highly specialized synthetics, for example, for highly loaded diesel engines.
In addition to "five" - synthetics, there is a similar semi-synthetics. Why not use it? Of course, you can also use liquid mineral water, add thickeners there, a synthetic component with a modern set of additives - and you get a completely standard semi-synthetic in winter, for example. However, it is known that its parameters in any case will be lower compared to synthetics. After all, the oil base plays an extremely important role, setting the physico-chemical base.
A well-known analogy can be traced with gasoline. There is a technology by which a lot of additives are added to low-octane A-80 gasoline in an artisanal way and AI-98 is obtained. But, having worked on such fuel, the engine will soon require repair: at least it will be necessary to flush the injector and replace the spark plugs. After all, it is quite clear that full-fledged gasoline of the highest quality will be obtained only through the use of appropriate technologies.
Viscosity
This characteristic is of paramount importance for a lubricating fluid. This parameter defines the maximum oil application temperature. Therefore, which oil is better: 5W30 or 5W40 (winter or summer) is determined precisely by this parameter. If the indicator is low, the lubricant should not be too viscous to cold start the motor with a starter and pump it through the pump. In high-temperature conditions, the oil, on the contrary, should not have too low a viscosity in order to be able to maintain a constant required level of pressure in the system and form a film that protects against friction around the parts.
So, they are divided into:
Winter. With a low viscosity, the engine will start easily, but the lubricant will not work effectively at high temperatures.
Summer. Cold start will be problematic at temperatures below zero degrees, however, with high viscosity, the motor will be reliably and stably lubricated in warm and hot weather.
All season. When it's cold outside, the oil exhibits the quality of winter lubrication, and when it's hot - summer.
All seasons are becoming more common, replacing the first two types, since now there is no need to change the oil every time the season changes. At the same time, they show themselves to be more efficient and energy-saving. An example of such a lubricant is 5W40 oil (synthetic).
Other characteristics
Of course, other characteristics are also important for oil: detergent, antiwear, anticorrosion and antioxidant (additives are used for this). However, viscosity is one of the main values. Many modern additives increase the price. Therefore, you should always pay attention to this parameter and choose the optimal ratio of lubricant properties and future engine operating conditions.
The main prescription that should be followed when choosing is the requirements of the vehicle manufacturer. They are listed in the user manual. Typically, they not only contain information about the specific properties that should be inherent in the lubricant used, but also offer specific brands of oils with recommendations for using them. Shell oil (5W40, 5W30 or other type) is often found in the manual. At the same time, if your car is far from new, and you have little information about its operation, then you can choose the brand for the engine or transmission yourself.
1999 SAE standard
What do those cryptic SAE letters stand for? From English, the abbreviation translates as "Society of Automobile Engineers" (Society of Automobile Engineers). This is an international standard that viscosity must comply with. For example, in 1999 the requirements of the standard were as follows.
According to the oils, they determine the correspondence to a certain season. It is calculated at low speeds from twenty to one hundred degrees and separately at one hundred degrees.
Starting properties are revealed through resistance at and the possibility of obtaining revolutions. Depending on the viscosity and class, they are determined at temperatures from ten to thirty-five degrees below zero and high shear rates (105s-1), that is, the conditions for working in crankshaft bearings during cold start are considered.
Pumpability determines the rate of passage of lubricant to rubbing parts during a cold start, as well as the possible risk of engine breakdown during a cold start due to the rotation of the liners. The indicator is considered at negative temperatures from fifteen to forty degrees and at low shear rates (10s-1). Under these conditions, the lubricant spreads in the sump to the oil receiver when starting a cold engine.
Viscosity at high temperature reveals the real indicator during operation of highly loaded motors in the warm season. Thus, anti-wear characteristics, losses due to friction and the impact on the efficiency of the motor are visible. It is fixed at high shear rates (106s-1). Under these conditions, the crankshaft bearings operate under high temperature and load.
SAE classification
This is the SAE specification, which determines in various conditions. There are currently six winter classes and five summer classes. Winter is easy to identify by the presence of the letter W (“winter”, which means “winter” in English). The higher the viscosity, the larger the numerical index will be.
Winter viscosity is indicated by 0W, 5W, 10W, 15W, 20W. 25W.
Summer - 20, 30, 40, 50.
Consider 5W40 oil as an example.
Its characteristics are as follows. Class - viscosity 5W. As you know, it can be used in the winter, that is, it depends on this indicator how easy it will be to start the engine in the cold. Thus, in order to understand which oil to fill in in winter, you need to pay attention to this particular indicator.
The number "40" reveals summer performance, that is, the ability of the engine to operate at high temperatures.
If, as in our example, there is a designation of both one and the other classes (that is, motor oil 5W40, as well as 5W30), this indicates the all-weather nature of its use.
How to choose a winter class
When choosing a viscosity, they are primarily guided by the instructions of the car manufacturer. If there are none, follow the general recommendations.
When choosing the best oil for winter, you need to take into account the conditions under which the vehicle will be operated.
Then problems with starting in winter and negative consequences for the motor (for example, rapid wear and jamming at startup, which can occur under oil starvation conditions) can be avoided, regardless of whether you have 5W30 or 5W40 filled in for the winter. It must be understood that when starting the engine, even if this does not happen in severe frost, but with a positive mark on the thermometer, it takes time for the oil pump to pump through the lubrication system so that the liquid enters all rubbing parts and channels. Until this time, the engine has been running in conditions of lack of oil. Therefore, friction and wear are greatly increased. The more the lubricant can keep fluid in low temperature conditions, the better the protection for the motor will be provided.
How to choose an all season
Winter properties are displayed on the left side, and summer properties are displayed on the right. Thus, wondering which oil is better - 5W30 or 5W40 - in winter, you need to pay attention only to the indicator on the left, and in this case it is the same.
Therefore, you should pay attention to the difference in summer mode and select the appropriate option depending on the operating conditions of the vehicle.
Viscosity-temperature properties
Ensuring the engine start without heating, free pumping of oil through the system and, as a result, stable lubrication of all rubbing parts at the maximum possible loads and ambient temperature depends on this indicator.
Even in a temperate climate, the change in winter temperature to the greatest warming up is up to one hundred and ninety degrees. Therefore, seasonal oils must be changed depending on the time of year. However, with the advent of all-weather seasons (they include, for example, motor oil 5W40 and 5W30), the problem was removed. Thanks to their additives, they are able to exhibit the required properties at various temperatures. That is, with a negative value, they are like winter oils, and with high positive values, they are like summer oils.
Additives
Additives do not greatly increase the viscosity at low temperatures, but they increase it strongly at high temperatures, when the number of macropolymer molecules increases significantly. In all seasons (which include 5W30 grease and 5W40 oil), the characteristics lie in the temporary possibility of changing its viscosity, also relative to shear rate. When the speed decreases, it increases, and when it increases, it decreases.
Most of all, this property is manifested at low temperatures, but it is also preserved at high temperatures, which has good consequences for the engine: low viscosity when the engine is cold makes it easier to descend, and when it is warm, energy loss due to friction is reduced, thereby saving fuel.
Low temperature
The low temperature characteristic of an oil is revealed through the pour point when the lubricant stops flowing. This indicator is realized when the temperature is five to seven degrees below that at which fluidity was possible.
Most often, solidification occurs due to the formation of paraffins in the chilled lubricant.
Which oil is better: 5W30 or 5W40 (in winter)
Based on the foregoing, it is clear that in the cold season, both species manifest themselves in the same way. Therefore, both one and the other type of lubricating fluid are perfect for winter.
The selection of engine oil is an important task for any motorist. The simplest tip for oil selection is to follow the advice of the car manufacturer. But when it is not possible to fulfill this recommendation, then you have to deal with the properties of the oil and its markings.
In this article, we will look at 5w30 and 5w40 engine oil and try to figure out what is the difference between these two brands.
The first number from the marking of engine oil characterizes its viscosity when used in the cold season, and the second part characterizes the fluidity of the oil in the warm season, at high temperatures. This marking characterizes engine oil according to the widely used SAE (American Association of Auto Engineers) classification. Two numbers in the marking mean that both types of oils are all-weather. This versatility is the reason why 5w30 and 5w40 oils are so popular with motorists.
Engine oil marking according to SAE classification
Viscosity at low temperatures. This most important property is described by the first part of the 5W index, where W is winter. At low temperatures, engine oil, like most fluids, thickens. The stronger the viscosity, the more difficult the operation of the oil pump. For the types of oil we compare, the first index is the same. When turning, the maximum viscosity of such a lubricant at -35 ° C is 6600 MPa, and when pumping, the indicator reaches 60,000 MPa.
high temperature viscosity. This is the second part of the oil label. According to the SAE classification, for 5w30 at 100 ° C, the oil viscosity (kinematic) will be in the range of 9.3 - 12.6 mm sq. / s. For grease type 5w40 12.6 - 16.3 mm sq./sec. High-temperature viscosity is characterized by another indicator: the minimum viscosity at a certain shear rate (10 6 s -1). For 5w40 oil, this figure (3.50) is also higher than for 5w30 (2.9).
What is the difference between 5w30 and 5w40
As already mentioned, 5w40 oil is more viscous and less fluid at high temperatures. That is, when the piston passes, the film remains thicker on the cylinder walls than when using 5w30. This is a basic difference between 5w30 and 5w40 as they behave the same at low temperatures. However, a thicker film is not always a plus.
Marking engine oil 5w30 and 5w40 on the canister
What happens if you use oil with a higher or lower high temperature viscosity in the engine than indicated in the user manual:
- With a higher viscosity, the resulting film on the internal surfaces will be larger than required. In some places, the lubricant simply may not flow due to too much viscosity. This, of course, is bad: it can threaten premature wear of parts, an even greater increase in the operating temperature of the engine. Such troubles threaten if you fill in the 5w40 brand where 5w30 is recommended.
- In the opposite case (using 5w40 instead of 5w30), less lubricant is consumed for waste. In principle, this lengthens the service interval, as indicated by some manufacturers and sellers of motor oils. But, if the car manufacturer recommended 5w40, then the 5w30 brand may form a too thin film on work surfaces. As a result, too rapid wear of the engine cylinder walls and piston rings can occur.
Video about the difference between 5w30 and 5w40
What is better 5w30 or 5w40
The purpose of using engine oil is to form an oil film on all rubbing engine parts. Very small gaps (a few microns) in the engine between rubbing parts require constant high-quality lubrication, excluding dry friction. What brand of lubricant is best for your car, only the manufacturer knows. When recommending a certain type, manufacturing companies take into account not only the characteristics of the oil, but also the design features of the engine itself. Therefore, it is best to follow the manufacturer's recommendations.
It should also be borne in mind that in addition to the SAE classification, lubricants must also meet the requirements of other systems: ACEA, API. Labeling for these classification systems is always indicated on the packaging, but attracts less attention.
As for specifically 5w30 or 5w40, we can say the following. 5w40 oil keeps the film perfectly and eliminates dry friction. It is well suited for modern motors with high thermal stress. 5w30 oil has a lower viscosity. It makes it easier to start the engine in cold weather, but becomes too fluid in hot weather. At a temperature of about 120 - 140 degrees in the engine, the viscosity of 5w40 auto-lube is 1.5 times higher than that of 5w30.
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!
