Lubricants that are intended for use in gearboxes and drive axles are called transmission oils. Motor oils for transmission and engine are classified the same way. The main characteristics of the oil are: viscosity parameters, performance indicators, corrosion resistance. Gearbox lubricants, like regular ones, have their own markings. Drivers should know what it means.

Transmission oils can be classified according to five different specifications: SAE, API, ZF, MIL, and specific vehicle manufacturer approvals. All gearbox lubricants must meet modern requirements for oil fluids. Gear oil 75w90 is one of the most common petroleum products.

Viscosity indicators 75w90

According to SAE, oils are divided into types depending on the viscosity index. The breakdown of oil 75w90 is as follows:

• 75w - indicates how fluid the car oil is in cold conditions. The smaller the number in front of the letter, the more fluid the oil is. The minimum temperature limit is minus forty degrees;
• 90 – characterizes viscosity at high temperatures. The maximum temperature limit is plus thirty-five degrees.

For what reason is SAE 75w90 so common in Russia? Is it possible to make an oil that can be filled in an even wider range? temperature range? Everything is somewhat more complicated. Protection of contacting parts from friction directly depends on the quality of lubrication. Though this characteristic with an increase in the viscosity index it only improves, and the law of resistance begins to operate. The gearbox loses more power because it needs to expend energy to squeeze the oil out from under the teeth. Also, the viscous grease becomes too thick in winter. Thinner oil feels better in cold conditions, but forms a film with less strength and lubricates spare parts less well. To balance these 2 parameters, special additives are used.

In temperate climates, it is advisable to choose lubricants such as 75w85, 80w90, 75w90 BO. For hot conditions, it is optimal to use 75w140 oils.

Transmission fluid performs the following tasks:

• elimination of friction, scuffing, and other damage;
• reducing energy losses, increasing productivity;
• heat removal from contacting parts;
• reduction of noise and vibration from operating spare parts.

Between motor oils 75w90 from various manufacturers There is a difference in both characteristics and cost. Typically this petroleum product is synthetic. Sometimes manufacturers write on the canister that it is semi-synthetic gear oil. It has only one difference from synthetic, which is the small content of additives.

API classification

The API specification classifies oils based on their performance characteristics. All of them are divided into 6 types. Each type has its own index, this allows you to understand the scope of use and quality of the petroleum product. Today, GL4 and GL 5 motor oils are used in passenger car transmissions.

• GL 4 – intended for gearboxes with medium load. Used in mechanical spiral bevel transmissions. Oil can be poured into hypoid gearboxes at high speeds and low torques;
• “GL 5” - intended for gearboxes with heavy loads. Oil is poured into hypoid gearboxes. The composition contains many additives that resist scuffing, consisting of sulfur and phosphorus.

Rating of the best 75w90 lubricants for gearboxes

The following characteristics must be taken into account:

• Viscosity index. Motor oil must maintain its own viscosity in different temperature conditions;
• Temperature indicators. Any petroleum product has its own pour point and flash point. The lubricant must cope with its tasks over a wide temperature range;
• Maximum load. The more this parameter, the better the oil;
• Badass index;
• Welding load. The parameter must be at least 3,000 N;
• Wear characteristics. It is only relevant for API GL 5 lubricants; it must be at least 0.4 mm.

According to many car indicators Motul oil Gear 300 75w90 GL 5 is in 1st place. It perfectly protects parts from scuffing and forms a stable lubricating film. But in winter it is not recommended to pour this oil product.

Mobil Mobilube is in 3rd place. Test transmission oils showed that it provides good protection against wear, but is not suitable for use in cold weather.

Comparison of 75w90 with other oils

80w90

LS 80w90 is a universal transmission oil consisting of a base fluid and additives. LS 80w90 provides excellent performance. LS 80w90 is intended for rear axles vehicles with hypoid gearboxes equipped with limited slip differentials.

Advantages of semi-synthetic LS 80w90:

• formation of a strong lubricating film;
• effectively prevents the formation of foam, excellent compatibility with sealing elements;
• consistency of operating indicators over a long period, this significantly reduces the frequency of oil changes;
• excellent corrosion resistance.

75w80

High-quality synthetic Shell 75w80 is used in gear transmissions. The lubricant has a long service life and reliably protects modern transmissions.

Description of the advantages of the lubricant:

• increase in unit productivity;
• precise gear shifting in various operating modes;
• resistance to scuffing, wear, pitting;
• environmental friendliness.

75w140

75w140 GL 5 is a synthetic that was developed for high-load gearboxes. Used in manual transmissions of cars, vans, trucks, minibuses, and special equipment.

Pros of motor oil:

• ensures uninterrupted operation of the transmission;
• thermostable;
• creates a durable film of oil on contacting parts;
• resists corrosive effects;
• does not foam.

What are the consequences of changing GL-4 to GL-5?

“Four” is intended for transmissions operating under medium loads. “Five” is optimal for hypoid gearboxes and drive axles operating in harsh conditions.

It is worth remembering that GL-5 contains a large number of additives that resist scuffing. They do not go well with bronze synchronizers in the gearbox. If you change the “four” to “five”, your car will start with a grinding noise and will probably break down soon.

Now you know what the characteristics are oily liquid 75w90, when to use it and when to use other lubricants. Testing has shown that it is optimal for Russian climatic conditions. It is necessary to take into account the recommendations of the car manufacturer as specified in the operating manual. The manufacturer knows what kind of oil should be poured into the engine/transmission own cars, much better than all the others.

Why replace something that lasts a lifetime? Optimism goes away when you discover a mountain of dead mechanical and automatic boxes, taken from cars of one very famous company. Which? Well, it doesn’t matter... The important thing is that boxes have now become almost disposable! They try not to repair them, but to replace them entirely - how much would such a replacement cost without a warranty, can you estimate? Therefore, the box must be cared for and cherished and definitely pampered good oil. Best fully synthetic, viscosity grade 75W-90, grade API quality GL-4 - this is perfect for manual transmissions.

It's a pity, domestic transmission synthetics not visible on the shelves. Only imports are mainly European, mainly German. Instead of GL-4, manufacturers prefer to indicate GL-4+, GL-4/5, and GL-3/4/5. So we bought a dozen of them. The price ranges from an affordable 345 rubles for a liter can of Dutch NGN to 775 rubles for a French Motul Gear 300. Is it worth paying so much? That's why we arranged an examination.

WHAT DO WE CHECK?

In general, the oil in the box is easier to work with than in the engine. But there are a lot of problems: it is necessary to simultaneously form a thin film and ensure lubrication of the gears. Must be serious protection from scuffing and wear. Therefore, viscosity, composition, and a set of additives are important in the characteristics of the transmission.

WHY DID YOU CHECK?

And here is what it all started for. We officially declare: the oils are very different and clearly not from the same barrel. The difference in results for individual parameters is not by percentages, but by several times! And the effect does not always correspond to the price. The leader was immediately revealed - the ester Motul Gear 300 has the best performance in terms of welding load, scuffing index, and critical load. The wear is a little worse, but here it’s generally interesting: none of the tested oils met the GOST requirements for the TM-5 group. Why is that? Perhaps this is a consequence of a decrease in the content of sulfur and phosphorus in modern products, which previously determined high anti-wear properties. But the result obtained cannot be considered negative either: we choose oil for manual transmissions of the GL-4 group, where anti-wear indicators are not standardized at all by GOST.

And here is another nuance that was worth working for. It turned out that anti-wear and extreme pressure properties change in antiphase! At the level of intuition this is understandable. The basic principle of wear protection is to place something soft and sliding between the parts. To increase scuff resistance, the opposite is required. Therefore, an effective additive package must provide some compromise between two mutually exclusive factors.

Well, what's better? Our advice on the topic “What to choose?” - below. We have arranged the files of all participants in alphabetical order. But I have only one wish: do not dismiss “boxed” oils.

Until the box brushes you off.

The results differ from each other not by percentages, but by several times!

WHAT, HOW AND WHY WE MEASURED

Tribological parameters. Characterize protective properties oils during contact in gears. They are determined in accordance with GOST 9490–75 on a four-ball friction machine: three stationary steel balls at the bottom, one spins at a given speed at the top and a load presses on it. The structure is immersed in an oil bath in which the test oil splashes. And then the behavior of the balls and contact patches tells everything. For different types of transmission oils it is standardized by our GOST 17479.2–85 - there are generally accepted ways of interpreting the results of such tests. Certainly, foreign manufacturers We are not required to follow GOST, but we live in Russia, and therefore we can use the standards of this document to assess the quality of the oil.

This is the threshold for destruction of the oil film. GOST does not standardize its value, so let’s think simply: the higher it is, the better.

Scuffing and wear. The main troubles of gearing. They are characterized by a scuff index and a wear index. The index is not standardized - in general, the higher the better. The wear rate for GL-4 oils (TM-4 in our GOST) is not standardized, but for TM-5 (or GL-5 in our non-our language) it should be no more than 0.4 mm. In general, less is more.

The main parameter by which extreme pressure properties are standardized. It is defined simply: the balls are loaded and loaded until the friction machine stops. For TM-4 oils, the welding load must be at least 3000 N, for TM-5 - 3280 N. Let's take these numbers as an evaluation criterion.

Viscosity. At operating temperatures we evaluate the kinematic viscosity, at low temperatures - dynamic. By kinematic viscosity at 40 and 100 °C we calculate the viscosity index, which characterizes the degree of dependence of viscosity on temperature. The range of change in this viscosity at 100 °C for the 75W‑90 class is quite wide - from 13.5 to 24 cSt. The higher the viscosity at operating temperature, the, generally speaking, the heavier the motor. The lower the dynamic viscosity at negative temperatures, the faster the box will warm up and the better the car will drive.

Pour point. Everything is simple here: the lower, the better.

Flash point. Together with the pour point, it characterizes to a certain extent the stability and quality of the base oil. The higher it is, the usually better base, - which means we can expect that the resource of such oil will be large.

QUESTION ANSWER

Are these types of oils suitable for automatic transmissions?

No good. Designed for automatic transmissions special liquids with other properties. It is very important to follow the manufacturer’s recommendations, because ATF fluid ensures the operation of a torque converter, which requires strictly specified viscosity-temperature characteristics. And for manual transmissions these requirements are much more relaxed.

What is the difference between GL-4 and GL-5 oils? Or, in our opinion, TM-4 from TM-5?

According to GOST 17479.2–85, the purpose of TM-4 group oils is cylindrical, spiral-bevel and hypoid gears operating at contact stresses up to 3000 MPa and oil temperature in the volume up to 150 °C. And the recipients of TM-5 oils are hypoid gears operating with shock loads at contact stresses above 3000 MPa and bulk oil temperatures up to 150 °C. Hence the differences in the required protective properties discussed in the article. Therefore, in particular, switching from GL-4 to GL-5 and back is unacceptable: these are different oils with different properties.

Will using a more viscous oil reduce transmission noise?

Yes, it will reduce it if the noise is caused by increased gaps in the box components. But within reasonable limits, of course. With a high degree of wear, even the most viscous oil will not help.

Should I chase synthetics? Or is the situation the same as with motor oil?

Synthetics are more stable and therefore guarantee greater resource. In addition, it has more high index viscosity, so the low-temperature properties of such oils are better. So there is a certain analogy with motor oils.

Why are there such large numbers in the SAE designations if the weather outside is the same as for the engine?

The numbers indicate the average viscosity range for the oil grade in Saybolt Second Universal Unit (SSU). For transmissions they are taken directly, for motors they are divided in half.

All tables open in full size at the click of a mouse.

Question about mixing - is it possible or not?

It depends on what you mix. Oils of the same SAE and API groups can theoretically be mixed, but in practice we do not recommend it.

Is flushing necessary when changing the oil?

If it was originally flooded good synthetics, then it is not needed.

Is it possible to fill GL-5 into a manual box?

GL-5 oil is intended for heavily loaded high-speed hypoid gears. Its enhanced extreme pressure and anti-wear functions are provided by an increased concentration of additives based on sulfur and phosphorus, which are aggressive towards non-ferrous metals. But in practice, transmission elements are individual, and therefore, in certain cases, the automaker may allow the use of one type of oil in all transmission components.

OIL IN A MANUAL TRANSMISSION: WHICH IS BETTER TO CHOOSE?

Nomination "Extreme"

The winner in this category guarantees protection of the box under maximum loads.

Gold from Motul Gear 300.

Nomination "Wear protection"

Gold from BP Energear And JB .

They took the silver ADDINOL,NGN And SRS .

Nomination "Energy Saving"

Guarantees the best efficiency. For the thrifty, in general.

Winners - Motul Gear 300 And Liqui Moly .

Silver Mobil Mobilube And ADDINOL .

Nomination "Fast warm-up"

These oils are better than others in overcoming the cold numbness after a night of hibernation.

Oil turned out to be the best SRS .

They took the silver BP Energear And Shell Spirax .

Nomination "Price/Quality"

Everything is clear from the name.

The winner is clear: NGN .

The Grand Prix

If speak about maximum protection(even for sports car gearboxes), it’s difficult to compete with ester oil here.

Winner - Motul Gear 300 .

Silver Castrol Syntrax, Mobil Mobilube, Eurol Transyn .

The anti-wear and extreme pressure properties of oils appear in antiphase.

REPRESENTATIVES

ADDINOL Gear Oil GH 75W-90

Germany

Price 1 l - 420 rub.

SAE 75W-90, API GL-4/GL-5

Approvals: MIL-L-2105D, VW 501 50

There is not a word in Russian on the label! One of the serious advantages is one of the highest levels of wear protection. But here there is a fly in the ointment - modest results on the scuffing index and welding load. And low-temperature properties are not the best.

Reasonable price.

Relatively low protective properties against scuffing.

BP Energear SGX 75W-90 Winner in the Wear Protection category

Belgium

Price 1 l - 470 rub.

SAE 75W-90, API GL-4+

Approval: Suitable for VW 501 50

The wear protection is the best, and the scuff protection is worse than most. In terms of wear, it comes very close to the very strict GOST requirements for oils of a higher group - TM-5. Good low temperature properties and highest flash point.

The best wear protection, affordable price.

Low values ​​of the scuffing index.

Castrol Syntrax Universal Plus

Germany

Price 1 l - 550 rub.

Approvals: MAN 3343S, 341E3; Scania STO 1:0; MB-Approval 235.8; ZF TE-ML 02B, 05B, 12B, 16F, 17B, 19C, 21B; SAE J2360

One of best performance Welding protection is combined with satisfactory wear protection. Very low pour point - with the lowest viscosity index. At the same time, the highest flash point promises a long service life.

+ High weld load provides long-lasting protection against scuffing; low pour point.

- Low viscosity index.

Eurol Lubricants Transyn Synthetic

Netherlands

Price 1 l - 420 rub.

SAE 75W-90, API GL-3/4/5 & MT-1

Approvals: Meets ZF TE-ML 01, 02, 05, 07, 08, Volvo 97310, Scania STO 1:0 BOX; MAN 341 TL/341 Type Z-3; MAN 342 SL/342 Type S-1; MAN 3343 S/SL; MIL-L-2105 B/C/D; MIL-PRF-2105E; DAF ZF TE-ML 02 BOX.

Again, not a single Russian word on the can! But in the “not our” language, on the one hand, it is written in large letters that it is synthetic, and on the other, in much smaller print, it is semi-synthetic... What to believe? After the tests, we believe the second one more.

High welding load, even according to our strict GOST it passes as TM-5.

Worst wear indicator.

JB GERMAN OIL Hypoid Getriebeoel GL 4 plus Winner in the category “Wear protection”

Germany

Price 1 l - 520 rub.

SAE 75W-90, API GL-4/GL-5 & MT-1

Approvals: MAN 3343 Type S; Scania STO 1:0; ARVIN MERITOR 0-79-N; SAE J2360; MIL-PRF-2105E; ZF TE-ML 02B, 05B, 07A, 12B, 16F, 17B, 19C DAF IVECO

One of the leaders in the number of approvals from automakers, but it’s not clear from the description - “approved” or “complies”? Wear protection is excellent, and the scuff index is weak. Low temperature characteristics are on par. And at the same time the highest viscosity at operating temperatures!

Good wear protection and low temperature properties.

The worst badass index in the review.

Liqui Moly "High Performance Gear Oil" Winner in the category "Energy Saving"

Germany

Price 1 l - 620 rub.

SAE 75W-90, API GL-4 + (GL-4/GL-5)

Approvals: Ford ESD M2C 175-A; VW Norm 50150 (G50); ZF TE-ML 08

Very expensive, but overall an outstanding oil. Tribological parameters are average, low-temperature properties are good, but not the best, and the viscosity index is also relatively low. And what is the claimed “high performance”?

Convenient bottle with built-in grease nipple, good low-temperature properties.

Expensive for average parameters.

Mobil Mobilube 1 SHC Fully Synthetic Supreme Performance Gear Oil

Sweden

Price 1 liter - 750 rub.

SAE 75W-90, API GL-5/MT-1

Approvals: Approved MB - Approval 235.8, MAN M 3343 Type S; MAN 341 E3; ZF TE-ML 02B/05B/12B/16F/17B/19C/21B; JSC AVTODISEL YaMZ Gearbox. Meets Scania STO 1:0; ZF TE-ML 07A

Very decent results in terms of transmission protection level when high loads. But at the same time, the lowest viscosity index predetermines weak low-temperature properties. At the same time, viscosity at operating temperatures suggests relatively low friction losses in the transmission.

Good protective properties.

Very expensive! And the viscosity index is strangely low for synthetics.

Motul Gear 300 100% synthese Winner in the nomination “Extreme” “Energy Saving” Grand Prix

France

Price 1 l - 775 rub.

SAE 75W-90, API GL-4/GL-5, MIL-L-2105D

Ester-based oil immediately stands out from the rest. He has the most high performance in terms of protection against scuffing and welding, and in terms of oil film resistance. At the same time, operating viscosities do not steal extra “horses” from under the hood. By all indications - the leader of the test.

Best tribological performance in terms of critical load and scuffing protection.

NGN Synthetic Transmission Oil Winner in the “Price/Quality” category

Netherlands

Price 1 l - 345 rub.

SAE 75W-90, API GL-3/4/5, MT-1

Tolerances: answers MAN requirements 341/342/3343; Scania STO 1:0 BOX; MIL-L-2105 B/C/D-PRF 2105E; Volvo 97310; DAF ZF TE-ML 02; ZF-TE-ML 01/02B/05B/07A/08A

The oil with a name that is not very well known among us turned out to be the most inexpensive, but quite worthy. In terms of basic parameters, it is in no way inferior to more eminent ones, and in some ways even surpasses them. Therefore, it receives first place in the “Price/Quality” nomination.

Low freezing point and a sufficient level of basic physical and chemical indicators combined with an affordable price.

High viscosity at operating temperatures.

Shell Spirax Axle Oil S5 ATE

Switzerland

Price 1 l - 480 rub.

SAE 75W-90, API GL-4/5

Approvals: Approved Ferrari, Porsche

Declared for extremely loaded transmissions, however, the tribological performance in all respects is not outstanding. But good low-temperature properties and viscosity at operating temperatures correspond to the stated purpose.

Good protection against scuffing, relatively affordable price.

High viscosity at operating temperatures increases friction losses.

SRS Schmierstoffe Getriebefluid 5 L Winner in the category "Fast warm-up"

Germany

Price 1 l - 490 rub.

SAE 75W-90, API GL-4 Plus

An oil unlike any other. It is bright green in color, and its composition is clearly different. The highest viscosity index determines the leadership in low temperature properties. But the viscosity at high temperatures is also high - expect friction losses. Good wear protection.

Low values dynamic viscosity at low temperatures, good wear indicator.

High viscosity at high temperatures, not the highest extreme pressure properties.

Total Transmission Syn FE

France

Price 1 l - 550 rub.

SAE 75W-90, API GL-4, GL-5, MT-1

Approvals: Approved MAN 3343 Type S; Scania STO 1:0; ZF TE-ML 02B, 05B, 07A, 12B, 16F, 17B, 19C; SAE J2360; MB-Approval 235.8; MACK GO-J

High viscosity at low temperatures will lengthen the warm-up of the box in the cold. At the same time, the working viscosity is decent, which will increase friction losses, but will protect the bearings. Significant advantages are low freezing point and high flash point.

Good tribological parameters.

Far from the best viscosity index.

Sae 75w 90 is popular when it comes to caring for your vehicle. synthetic oil for manual transmission Despite the fact that today, more and more often, car manufacturers deny the need to change the oil in the gearbox, many car owners pay the necessary attention to this.

Characteristics of these liquids

In general, when starting a conversation about which transmission oil can be considered the best, you need to understand that there simply cannot be a universal solution. By and large, it all depends on the brand of the car, and what works great for one model will work poorly for another, or even be harmful. Not to mention that the types of gearboxes differ from each other. Wide range of offers from manufacturers lubricants allows you to create a rating of the currently most popular transmission oils for a wide variety of cars.

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How to choose the right lubricant?

Please note that lubricants, whose viscosity is less than 24 mm2/s, at a temperature of 100ºC, belong to SAE class 140, which means that they can only be used in areas with warm climates. If the car is intended to be used in cold winter conditions (from -10ºС to -45), then it is better to choose a class marked with the number 90.

I had to note that among all the variety, for some reason I did not find semi-synthetic gear oil domestic production, which would satisfy the needs of car owners. For the most part, German liquids are in demand, sometimes they are supplemented by other European brands (French or Dutch).

Despite the fact that the load on transmission fluid is still less than on engine oil, even in this case this product is required not only to provide high-quality lubricant, but also to protect the mechanism from premature wear and scoring. Therefore, the test included everything important characteristics, including viscosity and additives present in the composition.
It must be said that viscosity can be assessed in different ways. For example, under normal operating temperatures it makes sense to evaluate kinetic viscosity, and in the case of low temperature conditions– also dynamic.

The scale of viscosity changes at a temperature of 100ºС varies from 13.5 to 24 cSt, using 75w90 oil as the most suitable climatic conditions in our latitudes. Moreover, it is necessary to understand that a lower viscosity value, subject to negative thermometer values, means faster and better heating of the box, and therefore more convenient driving on frosty days.

So let's take a look at some of the gear oils on the market. The most popular synthetic oil was Castrol Syntrans Universal Plus sae 75w 90. It complies with API class GL-4/GL-5. And it is specially designed for use in manual transmissions and contains a whole set of effective additives that prevent oxidation of the product, as well as wear of the internal components of the gearbox. Judging by user reviews, it performed well in a wide range of temperature conditions, and there are practically no complaints about it in terms of wear protection.

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Relationship with other brands

Next in the rating is the Honda CVT, which is most suitable for this particular brand of car. They say that this product has shown neutrality with respect to sealing materials and is quite effective when the temperature drops sharply in winter.

A relative newcomer (since it appeared on sale in our stores not so long ago), this product is still designed for manual box transmission It has a synthetic base, which means it has a long service life. And the presence of an additive package with anti-corrosion, extreme pressure and anti-wear properties makes it a very good choice for any car.

It should be said that Zic oil was noted as one of the most suitable for the northern regions of our climate zone G-F Top 75w 90. Moreover, those car owners who used this brand of transmission fluid noted that the noise in the transmission that previously bothered them decreased significantly after this product was poured into the system. What’s especially pleasing is that the price of this product is quite affordable.

Another one of the representatives trademarkСastrol Syntrans Transaxle sae 75w 90 also has a completely synthetic base. This oil is not only suitable for use in manual transmissions, but is also intended for any other components where it is necessary to use a lubricant that meets API GL-4 class. Main disadvantage This lubricant has a high price, but for many the quality still outweighs.

Separately, it is worth mentioning the universal transmission fluid Total Trans SYN FE 75w90 corresponding API classes Gl-4, API GL-5 and MT-1. Viscosity index indicators indicate that even at very low temperatures the liquid does not thicken. In addition, it requires replacement much less frequently than some other oils in the same group.
For owners of Renault cars, it is recommended semi-synthetic oil for manual transmission Elf Tranself NFJ 75w80. We can say that the high price is the most significant drawback of this product.

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For owners front wheel drive cars recent release of domestic production performed well Total oil 75 w 80 BV. According to the manufacturer, it perfectly resists oxidation, maintaining its properties for the entire service life. However, it differs at an affordable price, which is important for many.
There is an opinion that noise in the gearbox can be eliminated by replacing the recommended transmission fluid (oils 75w90, 85w 90) with a fluid with a higher viscosity (80w 140, 85w 140). This opinion is explained by the fact that a denser layer of oil can partially smooth out irregularities in the worn teeth, however, it must be taken into account that this state of affairs will be compensated for by a significant increase in fuel consumption, especially noticeable in winter time. There will be inconvenience in difficult gear shifting, and therefore you will have to make more efforts during the trip.

The noise reduction effect can be achieved by adding additives with molybdenum or other components that reduce friction to the oil. But it must be said that this method does not always help and only if there is a slight degree of wear.

Of course, we must remember that you should not mix gear oils belonging to different classes. The same as synthetic-based oils with semi-synthetic or mineral oils. It is likely that the additive packages added to them by different manufacturers will be incompatible, resulting in the need to pay for repairs.

If there is a need to replace mineral oil with synthetic or semi-synthetic oil, it is better to first flush the system.

Flushing is done using the transmission fluid that is planned to be used later.

If this option seems too expensive, you can wash it with transformer oil or spindle oil. The oil should be changed every 50,000 - 70,000 km. However, this is for conditions that correspond to European road surface quality, and in the case of our roads these figures have to be revised. So, if in Germany the oil change in the gearbox can easily be done after eighty thousand kilometers, then for our climate and road conditions this figure is about twenty-five thousand.

Unless, of course, you want to delay transmission repairs as long as possible. In some cases, the lubricant needs to be changed even earlier. This is especially true if the transmission oil suddenly darkens or acquires a foreign smell - it is better to immediately contact a service center to check the reason for this change. You may be able to get away with an easy gearbox repair, then flush the system and refill fresh oil. The main thing is to keep abreast of events and do not forget to take care of your car, then the service life of your vehicle will increase significantly.

Transfer cases and drive axles are called transmissions. Transmission and motor oil have a similar classification. For TM, the main properties are: viscosity characteristics, operational and anti-corrosion properties, as well as lubricity and thermal-oxidative ability.

75W-90 Transmission Oil Review

Transmission oil, just like motor oil, has its own, which you also need to be able to correctly decipher. On the oil label present SAE classification And API, some have ZF classifier or MIL specification , and may also be approvals from individual car manufacturers.

All modern gear oils must comply with international classification SAE standard J306. 75w90 is the most commonly used viscosity grade among transmission fluids.

Viscosity characteristics 75w and 90

According to SAE, TMs are divided into types and, accordingly, their purpose depending on viscosity. Since we will be talking about 75W-90 gear oil, we will first of all look at its characteristics.

75W – this indicator known as “winter”, shows the degree of fluidity at low temperatures. The lower the value in front of the letter “w”, the more fluid the transmission is in the cold. For this type of oil, the threshold should be at -40 °C.

The second indicator of the viscosity range is 90 , also called “summer”, indicates the maximum tolerated positive temperature of the outside air at a temperature of 100 degrees Celsius. The parameter itself also does not reflect the true value, you just need to know that according to reference data, this threshold will be up to +35 °C.

It would seem why exactly 75W90 oil is the most suitable for our latitudes, why not create a universal one with an even wider temperature spectrum? But it's not that simple. Protection against friction between gear surfaces directly depends on the lubricity of the gear oil. Although this indicator significantly improves with increasing viscosity, the law of resistance comes into force, and transmission power losses increase due to the waste of energy squeezing it out from under the gear teeth. Also, viscous oil thickens very much in the cold. Less viscous, with sub-zero temperatures, feels good, but has less durable protective film and worse lubricating properties. To balance these two indicators, special additive packages are also used.

In the zone of moderate temperatures, it is better to focus on the viscosity class “90”, but “140”, that is, TM, the viscosity of which at 100°C is not lower than 24 mm2/s, may be preferable for a hot southern climate or heavy loads with high speeds.

Transmission fluid must perform the following functions:

• exclude friction, jamming, scuffing, pitting (deep metal corrosion) and other damage;
• reduce energy loss and increase efficiency;
• remove heat from friction surfaces;
• reduce noise and vibration during gear operation.

Therefore, TM 75W90 from different manufacturers, of course, is somewhat different in its properties, and, naturally, in its price tag. In addition, 75W90 gear oil is often synthetic, although in some cases, a number of manufacturers may indicate it on the label as semi-synthetic. But in fact, it differs from synthetics only in the content of synthetic substances of 20% - 40% and the amount of additive from 2 to 15%.

In addition to the fact that these fluids are classified according to the SAE system, there is a division of transmission oils according to API system with the index “GL” (in the Russian version - the index “TM”).

Performance properties of TM

API classification shows comprehensive assessment transmission depending on operational properties and is divided into six categories. Categories are marked with an index, which makes it possible to understand the scope and level of quality of the product. Today, in passenger car transmissions, only two groups of fluids are used – GL-4 and GL-5 (TM-4, TM-5 according to the domestic classification).

GL-4(or TM-4) - designed for medium-loaded gears. Used in manual transmissions and mechanisms with spiral bevel gears. The operation of such oils can be carried out in transmissions hypoid type at significant speeds, but small or moderate torques.

GL-5(or TM-5) – used for heavily loaded gears. Operation of oil with this standard is carried out in hypoid gears at low torques in combination with high speeds, subject to short-term shock loads. This oil contains a large amount of sulfur-phosphorus containing extreme pressure additive.

Also a very common oil is 75W90 marked - GL-4/5, the presence of two indices indicates application under different load conditions and different types mechanisms.

MIL specification

In addition to API classification, it is often used American MIL specification. For 75W90 it is MIL-L 2105 A, B or C. Confirms compliance with technical specifications all-season gear oils, analogue of API GL-4 or GL-5.

ZF transmission oil quality classifier

Also on the canister of 75W-90 oil you can see Z classifier, - This classification system for all types of vehicle transmissions. The designation is made by letters and numbers from ZF TE-ML 01 to ZF TE-ML 14.

What is the difference between GL-4 and GL-5 75W-90 oils?

As already mentioned just above, the purpose of TM oils GL-4(according to GOST 17479.2–85) - for use in transmissions with bevel and hypoid gears, operating at contact stresses up to 3000 MPa and oil temperatures up to 150 °C. By and large, these are gearboxes of front-wheel drive cars. API GL-5 - provides reliable operation hypoid transmission, working with shock loads at stresses above 3000 MPa. It is used in gearboxes with hypoid bevel gears and for final drives with cardan drives in drive axles (with limited slip differential LSD). This transmission fluid provides better protection under conditions of high loads and pressures.

Mistakes when choosing TM 75W90 and the difference between GL 4 and GL 5.

Key Feature is that 75W90 API GL-4 oils contain half the amount of sulfur-phosphorus additives than in similar ones, only a higher class. Such additives create a special protective coating on parts that prevents wear, but this substance is even stronger than the surface of parts made of copper or other soft alloys. Therefore, using TMs for purposes other than their intended purpose threatens to wear out the surface of an element made of soft metal. So, in those gearboxes where it is necessary to use 75W90 GL-4, but GL-5 is filled in, there is a rapid appearance of copper shavings, because synchronizers are made of copper, and the sulfur-phosphorus additive kills them.

Switching from GL-4 to GL-5 and back is unacceptable: these are different oils with different properties and purposes.

Rating of the best gear oils with viscosity 75W90

• Viscosity. The oil must maintain optimal viscosity both at low temperatures and maintain its astringent properties at high temperatures;
• Temperature characteristics. Each liquid has its own pour point and ignition temperature, TM should have the largest gap between these indicators;
. The higher this number, the better the product;
• Bully index. Unfortunately, there are no standards for this index, but the higher this value, the better the TM;
. According to GOST, this value should be no lower than 3,000 H;
• Wear indicator. This criterion is determined only for GL-5 class oil; it should be less than 0.4 mm.

The TOP of the best transmission oils does not take into account their cost, but is given based on reviews and comparative tests.

In many respects, gear oil Motul Gear 300 75W90 takes first place among all tested. This transmission has the highest protection against scuffing (the index is 60.1), welding, oil film stability without loss of engine power, and an average wear rate (0.75 mm). Although viscosity characteristics(especially at sub-zero temperatures) it can’t boast.

Temperature test of transmission oils 75W90

Second and third places are taken transmission fluids from Castrol (Syntrans) and Mobil (Mobilube). Oil Castrol Syntrans Transaxle 75W-90 GL-4 is used in gearboxes, in transfer cases and driving axles. It has good low-temperature fluidity, but compared to Mobile, the scuff index is quite high for a liquid of this class, but the wear level is even better than Motul (59.4).

TM Mobil Mobilube can be placed in third place, since it has good test results for the level of protection and wear at high loads, and therefore provides low friction losses at operating temperatures. But, unfortunately, it has an insufficient viscosity index at sub-zero temperatures.

The fourth result when testing transmission oil showed oil Total Transmission SYN FE 75W-90. Reviews about this fluid are also good, although since it is universal - it has API GL-4/GL-5, it will not be suitable for all gearboxes. This TM has a scuff level of 58.8, which is even better than the leader in the rating of gear oils 75W90. But it cannot boast of wear levels and good viscosity in low-temperature tests.

Semi-synthetic gear oil LIQUI MOLY Hypoid-Getriebeoil TDL 75W-90 GL-4/5 also performs well in tests; it especially stood out when tested at minus 40; its fluidity at such a low temperature will allow the gearbox and gearboxes to operate without problems. At the same time, others important indicators on the Middle level.

Synthetic oil ZIC G-F TOP We do not include 75W-90 in this rating because there is very little data on its wear and scuffing performance, although the temperature test passes excellently. This gear oil can be used in manual transmissions (including synchronized transmissions) and drive axles. According to reviews from car owners, it significantly reduces transmission noise, withstands extreme loads and has virtually no drawbacks.

It is also impossible not to pay attention to Transyn 75W-90 API GL 3/4/5 oil from the manufacturer Eurol, since, looking at the lack of real temperature tests and very high level wear - 0.94, has a good level of scuffing - 58.5 and is very popular among car enthusiasts.

As you can see, the range of 75W90 gear oils on the market is quite large and there is always something to choose for your needs and affordable price. But remember that you need to select not because your neighbor advised, but based on the needs of your car’s transmission and the characteristics of the transmission fluid itself.