In this article we will talk about gear oils, their types and applications. You will learn which oil is better to take for the summer and which for the winter. We will also talk about the dangers of replacing GL-4 with GL-5. is a lubricant for transfer boxes, which is created on the basis of petroleum products with the addition of additives or by the synthesis of chemical elements.

Explanation of SAE 75w90 by viscosity

Types of oils

Almost every car owner knows what it is transmission oil and why it is needed. Some choose the lubricant for their car themselves, others trust the experience of friends or, without bothering themselves with this matter, use the services of a service station. But not everyone knows what the letters and numbers in the name mean, what the composition of the oils is and what their price depends on. Oils can be synthetic, semi-synthetic and mineral.

"Mineralka", as it is popularly called, is a cheap gear oil with mineral base in the form of refined petroleum products. "Synthetics"(designated on the box as Fully Synthetic) is obtained by synthesizing chemical elements. Basis "semi-synthetics" are petroleum products with the addition of various additives (a drug that is added to improve operational properties). IN this list the most expensive is synthetic oil.

Did you know? At the beginning of the twentieth century, nigrol was used in the form of gear oil. Summer option was a residue from oil distillation, and the winter one consisted of asphalt tar and distillate oil.

When choosing, immediately pay attention to marking transmission oil (if it contains the letter “W”, as in SAE 75W90, then it is all-season), as well as the numbers before and after this letter. Numbers up to "W" show the fluidity of a liquid at low temperatures, numbers after "W"- viscosity range at a temperature of 100 degrees. The absence of numbers after the letter "W" means that it is winter oil. If the marking does not contain “W” (Winter), then you are holding only summer oil in your hands.

Explanation by viscosity

Let's move on to deciphering 75W90 transmission oils by viscosity. SAE (Society of Automotive Engineers) stands for Society of Automotive Engineers. Among other things, “SAE” sets the viscosity grade for gearboxes (namely SAE indicator regulates how “thick” or “thin” this oil is). Since we are considering gear oils, it is worth highlighting summer, winter And all-season lubricating fluid. To put it in plain language, viscosity is the ability lubricant stay on the surface internal elements mechanism while maintaining fluid fluidity. Too much depends on the viscosity of the oil to ignore it.

Synthetic oil 75W90 has an optimal viscosity ranging from -40 to +35 degrees. If we compare 75W90 oil and cheap mineral 85W90, the latter at a temperature of -12 degrees will have the same viscosity as 75W90 oil at -40. Impressive? Obviously, in one case the gears will be shifted with a very noticeable effort, and in the other - instantly.

Which oil to use in summer and which in winter

Most car owners use demi seasonal oils, which will perform their function at any temperature. If you are considering seasonal oils, then, first of all, select the oil specifically for your gearbox, and only then, depending on the temperature (for a harsh winter or a very hot summer). It's better to take it for the summer SAE oil with an index from 20 to 60, which feels great in the heat. IN winter time SAE gear oil marked from 0W to 25W is better suited.

Important! The required viscosity index for the gearbox is indicated in the vehicle's operating manual.

Difference between gl4 and gl-5 oils

Before proceeding to the next section, you should consider the temperature conditions of transmission oils.

The API gl-4 standard is defined for transmission oils that are used for gearboxes (both bevel and hypoid) and units in drive axles operating under moderate loads and speeds. It is better to focus on 75w90 GL-4, since it is more rational to use off-season oil.

The API gl-5 standard is intended for high-speed hypoid gears and drive axles that only operate when high temperatures ah and are subjected to short-term shock loads. For proper work vehicle Many factors influence, but the main thing is the condition of the engine, car body and transmission. It all depends on the attentiveness of the car owner. The most important thing is to change the transmission oil on time.

When choosing lubricating fluid There are two main factors to consider: load force and relative sliding speed. Semi-synthetic oil is golden mean between price and quality. This composition combines best quality“synthetics” and “mineral waters”.

The specified gear oil is capable of:

1. Ensure stable operation of the transmission at low temperatures.

2. Extend the service life of the gearbox.

3. Maintain performance over wide temperature ranges.

The most rational option would be to buy semi-synthetic gear oil 75w 90. From this we draw the following conclusions: API gl-5 provides better protection in conditions high pressure and loads. Oil of this type covers the requirements of the GL-4 standard. But, unfortunately, the classification of gear oils does not take into account technological features a number of gearboxes.

Interesting fact! Several decades ago, manufacturers lubricants used lead additives against wear. Now they have been replaced with sulfur-phosphorus additive packages, since lead had a negative impact on the environment.

And so, we have decided that gl-5 contains more sulfur-phosphorus additives than gl-4. These additives create special coating to protect transmission parts, which acts as a “shield” against wear. This coating is stronger than the copper surface and other soft parts it comes into contact with. As a result, we get wear not only of the protective layer, but also of the surface of the soft metal element. That is why some manufacturers of gl4 and gl5 lubricants indicate that this product is not intended for gearboxes with synchronizers (makes the engagement of the sliding clutch with a fixed gear wheel shockless). Synchronizers made of copper are susceptible to increased wear.

Interesting! IN domestic cars synchronizers are ordinary bronze, turned on a machine without any coating. After all, synchronizers work quite harsh conditions and any additional coating collapses very quickly.

Let's draw the following conclusion: gl-5 is intended more for hypoid gears, in which, to a greater extent, friction or sliding is present. Transmission API oil gl-4 is more suitable for gears that operate in conditions. This oil Designed more for cone and hypoid gears, which have a small axle displacement. It is suitable for gearboxes trucks, tractors and buses.

As you can see, there are no cases of real harm from gl-5, but it would be better suited for bridges, gl-4 - for gearboxes. Also worth noting is the viscosity of the oil. Gear oil 80w 90 shows normal viscosity at 100 degrees Celsius, holds the load well and has low-temperature properties.

Why is replacing GL-4 with GL-5 dangerous?

Gl-4 is intended for gearboxes, as it is capable of operating under conditions of moderate loads and speeds. Gl-5 is more suitable for hypoid gears and drive axles, which in turn operate at high speeds and heavy loads.

But! Gl-5 contains a lot of extreme pressure additives that do not combine well with the bronze synchronizers in the gearbox.

Most likely, if you fill the box with gl-5, very soon the car will start to turn on with a grinding noise, and soon it will completely “bend”. It should be noted that there are universal gl4 and gl5, which will work worse on the axle and gearbox than pure gl-5 or gl-4. If you want to save money, which I definitely don’t recommend doing, then you can buy 2 liters of gl-4 for the gearbox and 2 liters of gl-5 for the axle. But, again, this is more suitable for conventional gearboxes. For hypoid gearboxes, and to ensure the necessary resource in them, gl-5 is exclusively suitable. Now about the dangers. Most often, in service centers , gl-4 or gl-5 oil is poured into both the gearbox and drive axles, which usually leads to extraneous noise and leaking seals. What's the problem? The container into which the pump in the transfer case pumps oil is small, therefore, the oil passes through the bearing into the transfer case or out through the oil seal. On high speeds

Important! pressure and heat rise. Often, this leads to damage to the seals, so we conclude that the oil must be stable. Gl-4 should be poured exclusively into the gearbox, and Gl-5 - into drive axle units.

Incorrectly selected oils lead to wear of the protective layer and the surface of the element, consisting of soft metal! After reading the article, you will certainly be able to choose oil for summer, winter or all-season transmission fluid. At the same time, do not forget about the strong recommendations of the manufacturer of your " iron horse "After a detailed study, we found out that the optimal SAE 75W90 can be considered for the whole year, which will work equally well in hot and cold weather. Also, we did not ignore hypoid oil SAE 80W90, which also holds up well at both “plus” and “minus” temperatures. We looked at the dangers of incorrectly filling oil and how this action can harm the car.

In conclusion, I would like to say: “It doesn’t matter whether you have an expensive “synthetic” or a cheap “mineral”, the important thing is how well your car works with such oil.” Therefore, do not forget that if the same oil was suitable for all cars, then, I think, manufacturers would not be churning out so many varieties of transmission oils for gearboxes.

The difference mainly comes down to additive formulation, with GL-4 oils typically containing 3 to 4% EP sulfur-phosphorus additives and GL-5 oils typically containing 4.5 to 6.5%.

In view of this, GL-5 is recommended for more heavily loaded gears (for example hypoid), and also as a universal one for most mechanical transmissions, which do not have synchronizers made of non-ferrous alloys in their design. This is due to the fact that the extreme pressure additive package contains sulfur-phosphorus elements, which can cause corrosion of parts made of non-ferrous alloys.

Thus, typically GL-4 is used for synchronized gearboxes, and GL-5 oil is used for axles and gearboxes. For front wheel drive cars, because the fight against corrosion of synchronizers may be at odds with the protection of gears final drive, because they are in the same block.

Gear synchronization occurs by pressing the locking synchronizer against the cone gear wheel- the oil film is squeezed out and the rotation speeds are compared. The problem is that in this case the lubrication becomes semi-dry and the problem is not corrosion, but wear, so each transmission manufacturer adheres to its own recommendations.

Many owners prefer to sacrifice possible corrosion of synchronizers in favor of greater extreme pressure properties (especially in the case of high loads), i.e. choose the GL-5 specification, although the manufacturer prescribed GL-4. On this moment Texaco has a range of synthetic oils with double API specification GL-4/GL-5, being low-viscosity, they provide good lubrication hypoid transmission and are non-aggressive to non-ferrous metals, as a result, can be used in cases of both specifications.

Consumers often wonder: what is fundamental difference between gear oils of API GL-4 and API GL-5 standards? This article will help us understand a little.

Standard oils API GL-4 used for bevel and hypoid gears (gearbox), as well as for drive axle differentials operating at moderate speeds and loads.
Oils are the same standard API GL-5 used for high-speed hypoid gears and drive axles operating at high temperatures and heavy loads.

The main difference between these oils is extreme pressure additive content.

In most gear oils imported and domestic production additives containing sulfur, phosphorus, halogens and most often chlorine are used. This composition has an aggressive effect on the metal, forming compounds that have lower shear resistance during operation and lower melting temperatures than pure metals. Subsequently, sticking and seizing of contacting surfaces is prevented.

In oils GL-4 added anti-seize components of medium activity, with a concentration of up to 4% .
In oils GL-5 high activity extreme pressure additives have been added, and their concentration is already up to 6%.

A high concentration provides better extreme pressure properties and protection under conditions of high loads and pressures. Sulfur-phosphorus additives create protective covering on transmission parts. During operation, contact between the rubbing elements occurs through this coating and thus the parts are protected from wear. However, when in contact with non-ferrous metals, this coating turns out to be more durable than the surface of parts made of copper or other soft parts. As a result, not only the protective layer wears out, but also the surface of the soft metal element. Use of oils API categories GL-5 in boxes where API GL-4 oils are required causes 2-4 times more copper in the oil than API GL-4 oils. As a rule, as a result of such interaction, synchronizers made of copper are the first to be hit. They are subject to increased wear when using lubricants with a high content of sulfur-phosphorus additives.

Let's summarize:

In practice, there is no clear functional division between these oils. First of all, when choosing a transmission, you should follow the recommendations of the car manufacturer.

From application experience I can give a number general recommendations selection of gear oil:

- API GL-4- used mainly in gearboxes. Can also be used in gearboxes with integrated differentials ( front-wheel drive). Can also be used in bridges of older types of technology API GL-4, you should follow the manufacturer’s recommendations. Equipment operating under heavy and shock loads most often does not allow the use API GL-4

- API GL-5- used in gearboxes and transfer cases. Use in gearboxes can lead to failure of copper synchronizers.

API GL-4+ And API GL-4/5 - for gearboxes with integrated differential (front-wheel drive). These oils have better anti-wear properties and are less aggressive on non-ferrous metals.

On the market, drivers can find many various models products. 75w90 oil is very popular. In this regard, car owners are very often interested in what it is, what characteristics it has, and which brand is better to buy from? We will provide you with answers to these and many other questions.

What role does oil play in a gearbox?

Before talking about the characteristics of any oil, it is necessary to find out what the main tasks this liquid should perform. Its use is actually due to several reasons:

Serves as a lubricant for moving gearbox parts, while significantly reducing wear. Each 75w90 gear oil creates a protective film on the surface that prevents the appearance of microcracks, gouges and other defects on the surface of gears, as well as other parts of the gearbox.
Removes heat. During the operation of all parts, strong heat is generated. High temperatures can lead to incorrect operation The gearbox, accordingly, and its imminent breakdown. Oil does not allow this.
Effective corrosion protection. Almost all metals are vulnerable to the destructive effects of oxidizing agents. To prevent gearbox parts from rusting over time, it is necessary to use quality oil without water content.
The operation of this unit is associated with a high level of noise, which creates discomfort while driving a car. Transmission oil can significantly reduce vibration and noise from the operation of the gearbox.

Thus, the oil composition must be fluid enough to ensure complete lubrication, as well as not freeze in cold weather.

SAE viscosity parameter

One of the main characteristics that you should definitely pay attention to when buying oil is its viscosity. For ease of purchase by the Society of Automotive Engineers, a standard has been developed that divides all products into several groups depending on viscosity parameters.

Oils sold can be divided into summer, winter and all-season. The first are marked with the usual number (from 80 to 250), and the second are marked with the English letter W (from the word Winter - “winter”). You can buy 70W, 75W, 80W and 85W products on the market. However, period-specific oils are becoming increasingly difficult to find as they have been replaced by all-season products.

In their designation they have two numbers at once, separated by the letter W. Let's find out what 75w90 means. The first number 75W is the so-called winter indicator fluidity. The parameter indicates the maximum low temperature, at which the oil will perform the assigned tasks. For this oil the minimum working temperature is -40 degrees Celsius.

The second number (90) is the summer viscosity indicator. In practice it shows the maximum temperature environment at 100 degrees Celsius for the oil itself. According to reference data, this parameter is limited to 35 degrees Celsius above zero. Now you know temperature regime 75w90. Based on these parameters, we can conclude that the oil is ideal for use in temperate latitudes.

Performance characteristics

Decoding 75w90 gear oil by viscosity may not be the only designation. Many products are also classified according to API, which provides a comprehensive rating of transmission fluid based on performance characteristics. In total, six groups can be distinguished. IN modern cars products of only two of them are used:

GL-4 (or domestic classification TM-4). Such products are intended for medium-load transmissions. As a rule, oil of this class is used in manual transmissions, as well as in mechanisms using spiral bevel gears. Oils can also be used in hypoid-type gears, but only with low torque.
GL-5 (TM-5). They are used in heavily loaded transmissions, in particular in hypoid transmissions with low torque, but subject to short-term shock loads. The product is characterized by a high level of sulfur-phosphorus containing extreme pressure additive.

Many car owners will be able to find 75w90 GL 4/5 gear oil. Such transmissions can be used in different conditions loads, while most of them are universal option between GL-4 and GL-5.

What are the differences between oils marked GL-4 and GL-5

As mentioned earlier, the first and most important difference is the scope of application. GL-4 is designed to work in bevel and hypoid gearboxes. Contact stresses in such units do not exceed 3000 MPa, and the oil temperature is within 150 degrees Celsius.

GL-5 is used for the correct functioning of the hypoid transmission in combination with shock loads. Such devices operate at stresses above 3000 MPa. The oil is used in units with limited slip differentials, providing high-quality protection parts under conditions of high temperatures and loads.

Important distinctive feature GL-4 is a low concentration of sulfur-phosphorus additives in the composition. They create a very durable protective layer, which is much harder than some soft alloys such as copper. The use of GL-5 oil in boxes where it is necessary to use oil of a lower class is unacceptable. This will lead to a large amount of metal shavings and wear of spare parts.

What to look for when choosing oil

When purchasing, you should focus not only on the brand, the price of the product, but also familiarize yourself with several other important characteristics product. This may include:

Viscosity. Transmission oil must maintain its viscosity in a certain temperature range, properly performing its main functions. Here, when purchasing, be guided by the above-mentioned SAE classification.
The difference between the pour point and ignition temperature should be maximum. Be sure to take this into account.
Critical load. The higher the number, the higher the quality of the presented product.
Bully index (the higher the score, the better).
Welding load. According to GOST regulations, the parameter must be below 3 thousand newtons;
Wear indicator. Relevant only for products class GL-5. High-quality oil should have no more than 0.4 millimeters.

These are the main characteristics of 75w90 oil, which are worth paying utmost attention to.

Synthetic or semi-synthetic

Typically, drivers will find 75w90 synthetic gear oils on store shelves. At the same time, you can also find semi-synthetics. The first ones have best performance among all types of lubricants. The advantages of such products include:

Optimal operating temperature range.
Maintains fluidity when exposed to sub-zero temperatures.
Hydrolytic stability.
Low volatility and oxidation resistance.
Long service life.
High viscosity index.

A noticeable disadvantage for many car owners is high price synthetics, therefore alternative option is semi-synthetic oil, which is slightly inferior in performance to the product described above, but has more affordable price tag. In other words, the difference in synthetic content is about 20-40 percent, and the amount of additives can differ by 15 percent.

Gear oil rating 75w90

It’s worth noting right away that the best 75w90 gear oil is the one recommended by the manufacturer. IN technical manual you can find for your car necessary information. Such products are developed specifically for your foreign car, so they meet all requirements. But if cash squeeze, you can purchase another gear oil 75w90 GL-5 or GL-4 from a third-party manufacturer. The TOP described below will help you with this.

The product occupies one of the leading positions in numerous tests Motul Gear 300. Gear oil is characterized high index anti-scuff protection (60.1) and excellent welding performance. The oil film is different high stability, therefore optimally minimizing friction of parts. The wear indicator is 0.75 millimeters. A small drawback are poor viscosity indicators at sub-zero temperatures.

Castrol Syntrans Transaxle, which can be placed in second place, is very popular. Low temperature fluidity, sufficient high level bully and relatively low price make this gear oil popular with many drivers. The fluid also boasts a high wear level (59.4).

If for some reason you are not satisfied with Castrol products, order a product from an equally popular brand. Mobil Mobilube ranks third. The oil of this brand provides outstanding viscosity-temperature properties, optimal protection against thermal degradation and oxidation, and is also capable of operating at extended intervals Maintenance. Oil has API marking GL4/5.

One more universal oil according to the API is Total Transmission SYN FE. The level of scuffing is not far from the products described above. It is 58.8, which is an excellent indicator. Unfortunately, drivers note low fluidity at sub-zero temperatures and poor wear protection.

LIQUI MOLY Hypoid-Getriebeoil has good characteristics. It is worth mentioning separately the turnover rate. The oil retained its performance qualities even at a temperature of -40. The transmission extends the service life of components and perfectly protects gearbox components from rust.

If the priority is to reduce gearbox noise and ensure maximum protection from scuffing, we recommend purchasing ZIC G-F TOP. The oil can withstand extreme loads without problems, while performing excellently in wide range temperatures An alternative high quality option is Transyn gear oil, main feature which can be called a high level of wear - 0.94.

How not to buy a fake

Careful selection of oil based on characteristics and numerous parameters will be useless if you buy a fake produced in “handicraft” conditions. Such oil will not cope with its functions and can also lead to accelerated wear and further breakdown of the gearbox.

When purchasing, be sure to check the date of manufacture, the quality of the printed label and the presence of various markings. Plastic canister and the cap must have the manufacturer's signature design. First check on the Internet what the desired oil looks like. These few tips will help you buy original certified products.

Technical fluids used in manual transmissions transfer cases, drive axles - are called transmission oils. The classification of transmission oils has a similar structure to motor oils. But unlike them, the key parameters are: thermal-oxidative ability, lubricating function, anti-corrosion effect, as well as viscosity characteristics. In addition, gear oil, similar to motor oil, is marked. The packaging contains SAE classification and API, as well as possible approvals from individual automakers.

Production technology SUPROTEC Atomium

First digit and letter designation W (winter, winter) indicates the degree of fluidity at low temperatures. The lower the value, the more fluid the liquid will be in the cold. An indicator of 75 is equivalent to -40 °C.

The second number is the viscosity range. It is also called summer characteristic. An indicator of 90 corresponds to a plus temperature of 35 °C. It is worth noting that the heating level of the mechanisms can reach 100 °C.

Temperature range 75° most best option For climatic conditions Russia, why wasn’t a product created with even wider ranges of action, for example, from -60 to +45.50 °C.

The answer lies in the lubricity characteristics of the transmission oil. To maintain viscosity balance in different temperatures modes used special packages additives In other words, too liquid oil at low temperatures it feels great, but at the same time it protects and lubricates the gears less well; on the other hand, too viscous oil means a loss of transmission power and wastes energy on squeezing transmission fluid out from under the teeth. It was possible to maintain a balance in this dilemma only in this temperature range. There are other variations of transmission fluids. For example, for hot southern climates and heavy loads at high speeds, you can use gear oil with parameters 85w140.

Manual transmission oil GL 4 - features

Gear oil API GL 4- created for medium-loaded gears. Main area of use – mechanical boxes gears, mechanisms with spiral bevel gears. In addition, this type of oil can be used in transmissions hypoid type. In this case, a significant speed must be compensated by a small or moderate torque.

The key point for API GL-4 oil categories is that they contain half as much sulfur-phosphorus additives as compared to GL-5 technical fluids. The presence of these categories of additives allows you to create a unique protective coating. Working contact between the moving elements of the transmission is carried out directly through this protective film. Parts are protected from wear. The service life is increased.

It is worth noting that more content sulfur-phosphorus additives can adversely affect transmission parts consisting of copper alloys and other soft materials. Their wear in this case increases by 1.5-2 times. Buy gear oil GL-4 for your car only if the car manufacturer has indicated free use in the operating certificate.

Transmission fluid GL 5 – scope of application

Gear oil API GL 5- used in heavily loaded gears. Mostly technical fluids with such standards are used in hypoid gears, at low torque, but in combination with high speed. In addition, transmission elements may be subject to short-term shock loads. Standard GL 5 is a high content of sulfur-phosphorus containing extreme pressure additive.

Thus, the fifth series gear oil provides better extreme pressure properties, as well as protection under conditions of high loads and pressure. But to the same extent, it is impossible to say 100% that the GL-5 standard completely covers the performance of the GL-4 modification.

Here, first of all, it is necessary to take into account the material of manufacture of transmission parts, technological features of the work, the degree of current wear, and the intensity of current operation.

Comparison of GL 4 and GL 5 oils - can one be replaced by the other?

The purpose of GL-4 oils is stable work bevel transmission and hypoid types of gears. The maximum contact stress is 3000 MPa, while the temperature is up to 150°C. In general, we can say that these are front-wheel drive gearboxes passenger cars. Having purchased gear oil GL 5, you will provide efficient work hypoid transmission together with shock loads. In this case, the stress can exceed 3000 MPa.

It is worth noting that the transition from GL-4 to GL-5 and back is not allowed - this different oils with different properties and purposes. As already indicated above key feature- this is the content of sulfur-phosphorus additives. In the GL-4 standard there are half as many of them. Therefore, if GL-5 is poured into the gearbox instead of GL-4, then a rapid appearance of copper shavings, since synchronizers are mainly made of copper and its alloys, and sulfur-phosphorus additives kill instantly.

Comparison table of characteristics of GL-4 and GL-5 gear oils

Criteria	API GL-4	API GL-5
Additives (phosphorus grey)
Gearbox type	Medium loaded, Bevel transmission	Heavily loaded, Hypoid transmission with shock loads
Maximum voltage	Up to 3000 MPa	Over 3000 MP
Torque and speed	Moderate torque and significant speed	Low torque combined with high speed