Description:
5 min
Additives for automatic transmission
Strictly speaking, the oil prescribed by the car manufacturer already contains all the additives necessary for its components and assemblies. The substances produced by third-party chemical manufacturers are more correctly referred to as "additives".
Classification Of Additives And Their Functions
The use of additives for automatic transmissions pursues specific goals aimed primarily at improving their operational qualities. The use of automotive chemicals should lead to the following results:
• Reduction of vibrations and noise during operation of the automatic transmission.
• Reduction of jerks (so-called "kicks") during gear shifts.
• Restoration of wear and, as a result,
• Extension of the service life of the transmission.
Although automotive chemical manufacturers often claim that their products solve problems comprehensively, possessing cleaning, anti-friction, and other positive qualities, additives for automatic transmissions can be divided into the following groups:
1. Flush additives. Used for the same purpose as engine flush: added to the transmission fluid before its replacement.
2. Leak-stop additives. The goal of their application is to restore the elasticity of seals and gaskets to stop oil leaks.
3. Restorative additives (revitalizants). They are intended to compensate for wear in transmission components, reduce clearances, and normalize the transmission's operation (smooth gear shifting, friction clutch engagement, etc.).
However, when it comes to the anti-friction qualities of additives (if claimed by the manufacturer on the packaging or in the product description), it is not so straightforward. The principle of operation of most automatic transmissions (primarily, classical planetary or variator types) involves the use of beneficial friction properties. Reducing the friction coefficient in them will result in slippage of friction elements or the variator belt.
Composition And Principle Of Action
Usually, manufacturers provide only partial information about the components and formulation of their products. By analyzing it, the additives themselves, and the effects they produce, one can draw conclusions about several groups of main active substances.
• High-molecular-weight polymers. They form a protective film that eliminates dry friction.
• Revitalizants containing fine particles of metals (mainly copper) and ceramics. They form a metal-ceramic layer that restores the geometry of worn parts and clearances between them.
• Molybdenum compounds. Molybdenum disulfide contributes to reducing temperature and noise, as well as increasing the elasticity of rubber seals.
The active substances of additives cover the worn friction surfaces, improving their adhesion and tribomechanical properties. According to the manufacturers of automotive chemicals, additives do not deteriorate the characteristics of the transmission fluid, acting "locally" and repairing only damages.
Thanks to the action of additives, some improvements in the operation of the automatic transmission are indeed possible: increased oil pressure in the transmission, improved gear shifting, reduced slipping, and the cessation of minor leaks.
Application Of Additives
From the brief description of the functions of additives for automatic transmissions, it can be understood that they are mainly designed for use in units with significant mileage. Using additives in new transmissions, even preventively, does not make sense: revitalizants have nothing to restore in them yet, and leak-stop additives will not improve the condition of already elastic rubber components. Moreover, it is highly undesirable to change the composition and consistency of the transmission fluid (the properties of which are carefully balanced considering the responsible application) as it may lead to a loss of fluid quality.
When using additives in units with mileage, it should be understood that chemistry is not a panacea but only an emergency and temporary measure that allows delaying repairs but does not eliminate malfunctions. Moreover, it is advisable to use additives when other possible malfunctions have already been ruled out. For example, jerks during gear shifts can occur not only due to faults in the components of the automatic transmission, but also due to issues with the throttle valve, electronic sensors, and engine control unit.
Flushing the automatic transmission should also be done with great caution. Car manufacturers have a good reason for not regulating this process: for normal operation of the automatic transmission, it is sufficient to timely replace the transmission fluid (not less than every 60,000 km for hydraulic or continuously variable transmissions).
In the case when the oil has been used for a longer mileage than recommended, or its usage history is unknown, there is a high risk of damaging the transmission during flushing. Deposits that are washed away by the additive can clog the oil channel, bypass valve, solenoid, depriving the automatic transmission of its functionality. It is much safer and equally effective in problematic cases to perform a partial transmission fluid replacement by replacing around 50% of the volume with new fluid, followed by replacing the second half after a short mileage (500-1000 km) - this is recommended by some car manufacturers.
Conclusions And Recommendations
Additives for automatic transmissions should only be used in extreme cases, when repair needs to be postponed for some reason, and not as a substitute for it. The protective layer formed by the active substances of additives significantly differs in its properties from the materials used in the components of the automatic transmission, which means that full restoration cannot be achieved. Moreover, despite the assurances of chemical manufacturers, sometimes this layer forms on functional components, increasing their size, which can lead to malfunctions.
It is necessary to strictly follow the recommendations for the use of additives, including their compatibility with specific types of transmission fluids, the temperature regime for filling (usually the transmission needs to be warmed up to operating temperature), usage period, and operating conditions.
Avoid using additives from unknown manufacturers, suspiciously cheap ones, or those that promise to restore "everything and anything," contradicting common sense and the laws of physics. Beware of counterfeits and unreliable trading points.