By FUCHS Lubricants South Africa
Increasing demands on improving fuel economy and lower greenhouse gas emissions are calling for more and more complex vehicle construction. For automatic transmission vehicles, technical developments mean that it is more important than ever to choose the correct ATF (Automatic Transmission Fluid) product to ensure the transmission works optimally over its entire life.
Never have there been as many types of transmission as in today’s vehicles. Today the focus is increasingly on the transmission working with the rest of the vehicle to provide better overall performance with greater fuel efficiency, lower emissions and a more comfortable driving experience.
Automatic transmissions contain many components made of different materials, and all have to work smoothly and reliably together. These include torque converters, planetary gearsets, centrifugal oil pump, seals, and clutch and brake sets.
There is a trend towards more gears, while alternative and often lighter materials are used. This is placing ever higher demands on ATFs, which are vital to transmission function.
An ATF is probably the most complex of all lubrication fluids.
The oil needs to cool and lubricate while also transmitting power and pressure. The requirements an ATF is required to meet may seem contradictory. For example, it needs to reduce friction and reduce wear on components, while also providing a carefully balanced friction level that enables the clutch and torque converters to work efficiently.
ATFs must increasingly last the entire life of the system without changing, have high anti-friction strength, good shear stability, be fluid at low temperatures and offer better oxidation stability. Meanwhile the oil should help boost fuel efficiency and reduce emissions in co-operation with each specific transmission solution.
Since the hardware construction in the automotive industry is becoming increasingly complex, it is no wonder that demands are being placed on the fluids that exclude universal solutions, for both new and old vehicles with an automatic transmission.
Costly failures or problem-free operation
Potential consequences of using fluids that have not been specially developed and tested for the automatic transmission in question include poorer acceleration, difficulty changing gear, excessive wear on components, and in the worst cases – a total and expensive gearbox breakdown. Some types of damage will not be immediately noticeable after changing the oil, but will become evident down the line.
On the other hand, the advantages of using the correct, specially-adapted ATF are considerable, including lower cost of ownership, reduced service requirements, lower maintenance costs, greater operational reliability, higher fuel efficiency and a better driving experience.
A complex process
Development and validation of ATFs are a complex process due to the wide range of performance requirements and the many different materials used in the components. OEM-specific tests and industry standard tests must be carried out to validate the ATF performance before final long-term testing of durability in transmissions and vehicles.
Tested, approved ATF oils with the right composition contain a balanced mixture of base fluid, performance-enhancing additives and viscosity modifiers, all of which serve important, very specific purposes. Important performance-enhancing additives in ATFs include friction modifiers, detergents and dispergents, foam, oxidation and corrosion inhibitors, pour point depressants, seal-swell and anti-wear additives.
The contents of these additives must be carefully balanced to ensure they work together and perform their specific functions. Specialist chemists create the complex compositions to ensure that the additives, base fluid and viscosity modifiers do not work against each other, so that the ATF can work in the intended way with the automatic transmission’s mechanical parts.
The comprehensive development and testing process guarantees the specially adapted ATF’s function in the transmission for the entire life of the vehicle.