Characteristics of Dextron 2 and 3 - what are the differences
Content
Fluid Differences Dexron 2 and 3, which are used in power steering and for automatic transmissions, is in terms of their fluidity, the type of base oil, as well as temperature characteristics. In general terms, we can say that Dextron 2 is an older product released by General Motors, and accordingly, Dextron 3 is newer. However, you cannot simply replace the old fluid with a new one. This can only be done by observing the manufacturer's tolerances, as well as the characteristics of the fluids themselves.
Generations of Dexron fluids and their characteristics
in order to figure out what are the differences between Dexron II and Dexron III, as well as what is the difference in one and the other transmission fluid, you need to briefly dwell on the history of their creation, as well as the characteristics that have changed from generation to generation.
Dexron II specifications
This transmission fluid was first released by General Motors in 1973. Its first generation was called Dexron 2 or Dexron II C. It was based on mineral oil from the second group according to the API classification - American Petroleum Institute. In accordance with this standard, base oils of the second group were obtained by using hydrocracking. In addition, they contain at least 90% saturated hydrocarbons, less than 0,03% sulfur, and also have a viscosity index ranging from 80 to 120.
The first additives that began to be added to the transmission fluid were corrosion inhibitors. In accordance with the license and designation (Dexron IIC), the composition on the package is indicated starting with the letter C, for example, C-20109. The manufacturer indicated that it is necessary to change the fluid to a new one every 80 thousand kilometers. However, in practice, it turned out that corrosion appeared much faster, so General Motors launched the next generation of its products.
So, in 1975, transmission fluid appeared Dexron II (D). It was made on the same base mineral oil of the second group, however, with an improved complex of anti-corrosion additives, namely, preventing corrosion of joints in oil coolers of automatic transmissions. Such a liquid had a fairly high minimum allowable operating temperature - only -15°C. But since the viscosity remained at a sufficiently high level, due to the improvement of transmission systems, this began to lead to vibrations during the movement of some models of new cars.
Starting in 1988, automakers began to change automatic transmissions from a hydraulic control system to an electronic one. Accordingly, they needed a different automatic transmission fluid with a low viscosity, providing a much higher rate of force transfer (response) due to better fluidity.
Was released in 1990 Dexron-II (E) (the specification was revised in August 1992, the re-release began in 1993). He had the same base - the second API group. However, due to the use of a more modern additive package, gear oil is now considered synthetic! The maximum low temperature for this liquid has been reduced to -30°C. Improved performance has become the key to smooth automatic transmission shifting and increased service life. The license designation begins with the letter E, such as E-20001.
Dexron II specifications
For Dextron 3 transmission fluids base oils belong to group 2+, which is characterized by increased characteristics of class 2, namely, the hydrotreating method is used in the production. The viscosity index is increased here, and its minimum value is from 110…115 units and above. That is, Dexron 3 has a fully synthetic base.
The first generation was Dexron-III (F). Really it's just improved version of Dexron-II (E) with the same temperature indicators equal to –30°C. Among the shortcomings remained low durability and poor shear stability, fluid oxidation. This composition is designated with the letter F at the beginning, for example, F-30001.
Second generation - Dexron-III (G)appeared in 1998. The improved composition of this fluid has completely overcome vibration problems when driving a car. The manufacturer also recommended it for use in hydraulic power steering (HPS), some hydraulic systems, and rotary air compressors where a high level of fluidity at low temperatures is required.
The minimum operating temperature at which Dextron 3 liquid can be used has become be -40°С. This composition began to be designated with the letter G, for example, G-30001.
Third generation - Dexron III (H). It was released in 2003. Such a liquid has a synthetic base and also a more improved additive package. So, the manufacturer claims that it can be used as a universal lubricant. for all automatic transmissions with controlled torque converter lock-up clutch and without it, that is, the so-called GKÜB for blocking the gear shift clutch. It has a very low viscosity in frost, so it can be used down to -40°C.
Differences between Dexron 2 and Dexron 3 and interchangeability
The most popular questions about Dexron 2 and Dexron 3 transmission fluids are whether they can be mixed and whether one oil can be used instead of the other. Since the improved characteristics should undoubtedly affect the improvement of the operation of the unit (whether it be power steering or automatic transmission).
| Interchangeability of Dexron 2 and Dexron 3 | |
|---|---|
| Replacement / mix | Terms |
| For automatic transmission | |
| Dexron II D → Dexron II Е |
|
| Dexron II D → Dexron III F, Dexron III G, Dexron III H |
|
| Dexron II Е → Dexron III F, Dexron III G, Dexron III H |
|
| Dexron III F → Dexron III G, Dexron III H |
|
| Dexron III G → Dexron III H |
|
| For GUR | |
| Dexron II → Dexron III |
|
The difference between Dexron 2 and Dexron 3 for automatic transmission
Before filling or mixing different types of transmission fluids, you need to find out what type of fluid the automaker recommends using. Usually this information is in the technical documentation (manual), for some cars (for example, Toyota) it may be indicated on the gearbox dipstick.
Ideally, only the lubricant of the specified class should be poured into the automatic transmission, despite the fact that from class to class of liquid there have been improvements in characteristics that affect its duration. also, you should not mix, observing the replacement frequency (if replacement is provided at all, since many modern automatic gearboxes are designed to operate with one liquid for the entire period of their operation, only with the addition of liquid as it burns out).
further it must be remembered that mixing fluids based on mineral and synthetic base is allowed with restrictions! So, in an automatic box, they can be mixed only if they contain the same type of additives. In practice, this means that you can mix, for example, Dexron II D and Dexron III only if they were produced by the same manufacturer. Otherwise, chemical reactions may occur in the automatic transmission with precipitation, which will clog the thin channels of the torque converter, which can lead to its breakdown.
The difference between Dexron II D and Dexron II E is thermal viscosity. Since the operating temperature of the first liquid is up to -15 ° C, and the second is lower, up to -30 ° C. In addition, synthetic Dexron II E is more durable and has more stable performance throughout its life cycle. That is, replacing Dexron II D with Dexron II E is allowed, however, on condition that the machine will be used in significant frosts. If the air temperature does not drop below -15 ° C, then there are risks that at high temperatures the more liquid Dexron II E will begin to seep through the gaskets (seals) of the automatic transmission, and may simply flow out of it, not to mention the wear of parts.
When replacing or mixing dextron fluids, it is necessary to take into account the requirements of the automatic transmission manufacturer, whether it allows reducing friction when replacing the ATF fluid, since this factor can adversely affect not only the operation of the unit, but also its durability, and given the high cost of the transmission, this is significant argument!
Feedback replacing Dexron II E with Dexron II D is unambiguously unacceptable, since the first composition is synthetic and with a lower viscosity, and the second is mineral-based and with a higher viscosity. In addition, Dexron II E is more effective modifiers (additives). thus, Dexron II E should only be used in areas with severe frosts, especially considering that Dexron II E is much more expensive than its predecessor (due to more expensive manufacturing technology).
As for Dexron II, its replacement by Dexron III depends on the generation. So, the first Dexron III F differed little from Dexron II E, so replacing the second "Dextron" with the third is quite acceptable, but not vice versa, for similar reasons.
Concerning Dexron III G and Dexron III H, they also have a higher viscosity and a set of modifiers that reduce friction. This means that theoretically they can be used instead of Dexron II, but with some limitations. namely, if the equipment (automatic transmission) does not allow a decrease in the frictional properties of the ATF fluid, replacing dextron 2 with dextron 3, as a more “perfect” composition, can lead to the following negative consequences:
- Increasing gear shift speed. But it is precisely this advantage that distinguishes an automatic transmission with electronic control from an automatic transmission with hydraulic control.
- Jerks when shifting gears. In this case, the friction discs in the automatic gearbox will suffer, that is, wear out more.
- There may be problems with the electronic control of the automatic transmission. If the switching takes longer than expected, then the electronic control systems can transmit information about the corresponding error to the electronic control unit.
Dexron III transmission fluids In fact, it should be used only in northern regions, where the temperature of using a car with automatic transmission can reach -40 ° C. If such a liquid is supposed to be used in the southern regions, then information on tolerances must be read separately in the documentation for the car, since this can only harm the automatic transmission.
So, the popular question of which is better - Dexron 2 or Dexron 3 is in itself incorrect, because the difference between them exists not only in terms of generations, but also in terms of destinations. Therefore, the answer to it depends, firstly, on the oil recommended for automatic transmission, and secondly, on the operating conditions of the car. Therefore, you can’t blindly fill in “Dextron 3” instead of “Dextron 2” and think that this automatic transmission will only get better. First of all, you need to follow the recommendations of the automaker!
Dextron 2 and 3 differences for power steering
As for the replacement of the power steering fluid (GUR), similar reasoning is valid here. However, there is one subtlety here, which is that the viscosity of the fluid is not so important for the power steering system, because the temperature in the power steering pump does not rise above 80 degrees Celsius. Therefore, the tank or lid may have the inscription “Dexron II or Dexron III”. This is due to the fact that there are no thin channels of the torque converter in the power steering, and the forces transmitted by the liquid are much less.
So, by and large, it is allowed to replace Dextron 3 instead of Dextron 2 in the hydraulic booster, although not in all cases. The main thing is that the liquid should be suitable according to the criteria of low-temperature viscosity (cold start-up with viscous oil, in addition to increased wear of the pump blades, is dangerous with high pressure and leakage through the seals)! As for the reverse replacement, it is not allowed for the reasons described above. Indeed, depending on the ambient temperature, the hum of the power steering pump may occur.
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When using power steering fluid, it is worth focusing on the minimum pumping temperature and the kinematic viscosity of the oil (for the durability of its operation, it should not exceed 800 m㎡ / s).
Difference between Dexron and ATF
In terms of interchangeability of fluids, car owners are also wondering not only about the compatibility of Dexron 2 3, but also what is the difference between Dexron 2 oil and ATF. In fact, this question is incorrect, and here's why ... The abbreviation ATF stands for Automatic Transmission Fluid, which means automatic transmission fluid. That is, all transmission fluids used in automatic transmissions fall under this definition.
As for Dexron (regardless of generation), it's just a name for a group of technical specifications (sometimes referred to as a brand) for automatic transmission fluids created by General Motors (GM). Under this brand, not only automatic transmission fluids are produced, but also for other mechanisms. That is, Dexron is the generic name for specifications that have been adopted over time by various manufacturers of related products. Therefore, often on the same canister you can find the designations ATF and Dexron. Indeed, in fact, Dextron fluid is the same transmission fluid for automatic transmissions (ATF). And they can be mixed, the main thing is that their specification belongs to the same group. As for the question of why some manufacturers write Dexron canisters and others ATF, the answer comes down to the same definition. Dexron fluids are manufactured to General Motors specifications, while others are to other manufacturers' specifications. The same applies to the color marking of canisters. It does not in any way indicate the specification, but only informs (and even then not always) about what type of oil was used as the base oil in the production of one or another transmission fluid presented on the counter. Typically, red means that the base used mineral oil, and yellow means synthetic.
