Explaining the complexity of automatic transmissions and the need for specialized ATFs.

The automatic transmission is the most complex component in an automobile and it is also one of the most expensive. Discover why the right transmission fluid is critical to the proper functioning and long-life of a step-type automatic transmission.

There are three types of automatic transmissions: a DCT (Dual-Clutch Transmission), CVT (Continuously-variable transmission) and step-type transmission (AT).

Main components of a step-type automatic transmission

To understand the basic operations of a step-type transmission you must know its main components:

  • Fluid pump: supplies pressured transmission fluid for many uses throughout the transmission. 
  • Planetary gear sets: provide the chosen gear ratio for the vehicle.
  • Clutches or clutch packs: engage and disengage the gear sets.
  • Torque converter: connects the transmission to the engine and multiplies the torque during initial acceleration. It uses two turbines which spin independently but which are fluid-coupled, allowing the engine to idle while the vehicle is stopped and produces smoother acceleration as it shifts through the gears.
  • Mechatronics: the brain of the transmission. It is a complex system of ports, valves and electronics that control all transmission functions.

How does a step-type automatic transmission work?

At idle in park, the pump components spin, providing the pressured fluid needed to operate the transmission.

When the vehicle is placed in drive, clutches connect the gear set for first gear to the wheels. When you release the brakes, the car begins to move. As the vehicle accelerates, second gear clutches and planetary gears are engaged.

After more acceleration, second gear disengages and the clutches and gears for third gear are deployed. All the gear combinations work the same way.

The mechatronic brain calculates the vehicle speed, the engine load and the position to the throttle and break, among other factors. It then sends high-pressure transmission fluid to engage the proper clutch packs and shift the gears.

The different functions of an automatic transmission fluid

The automatic transmission fluid (ATF) is critical to the good functioning of an automatic transmission.

The automatic transmission fluid has to do a lot of different jobs:

  • It acts as a hydraulic fluid to engage clutch packs and shift the gears.
  • It acts as a corrosion inhibitor and wear protection for the planetary gear sets.
  • It controls friction in the clutch packs and maintains it throughout the drain interval.
  • It provides lubrication to the hundreds of moving parts, even under high temperatures and extreme pressures.

To flawlessly perform these different jobs, an automatic transmission has to:

  • flow easily from -40°C to over 200°C even in fine valve assemblies;
  • have low conductivity and be compatible with all electronic components.

Do you know the right ATF for your automatic transmission vehicle?

The importance of selecting the right automatic transmission fluid

Modern ATF’s include friction modifiers, special agents for anti-wear and anti-corrosion agents and chemicals to enhance high-heat performance and maintain a specific viscosity.

Using the right automatic transmission fluid is critical to the performance and long-life of your transmission. Using the wrong fluid may cause excessive wear in pumps, gears and bearings leading to permanent damage and the need to replace your transmission. A single mechanical failure could disable the vehicle entirely.

Q8Oils ATF portfolio

The automatic transmission is one of the most complex components in your car and it is also one of the most expensive. That is why selecting the right transmission fluid is very important.

At Q8Oils we have a broad portfolio of high-performance automatic transmission fluids for all car brands:

  • Q8 Auto D VI: synthetic automatic transmission fluid for General Motors transmissions and other vehicles that require low viscosity ATF oil.
  • Q8 Auto JK: synthetic automatic transmission fluid for Aisin Warner transmissions. This product offers excellent thermal stability and improves overall transmission durability and cleanliness.
  • Q8 Auto MV: synthetic automatic transmission fluid that is compatible with vehicles that require low viscosity oil. This product is suitable for a wide range of European, Japanese and Korean passenger cars.
  • Q8 Auto CVT EVO: multi-vehicle Continuous Variable Transmission fluid for modern transmissions. This product is shear stable, offers extended drain intervals, excellent performance reserve and prevents slipping belts/clutches and breakdowns.
  • Q8 Auto DCT EVO: Dual Clutch Transmission fluid for modern transmissions. This product offers class-leading dual clutch and synchro friction control as well as superb protection of gears and bearings.
David De Mesmaeker

From our expert David De Mesmaeker

David has been working for Q8Oils since 2008 and is an expert in Heavy Duty Diesel Oils, Passenger Car Motor Oils, Automotive Transmissions, Agri & Off-Road and Anti-Freeze products.

Ask David De Mesmaeker



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