Special oil from TotalEnergies for dual-clutch transmissions
The concept of a dual-clutch transmission was first developed by French engineer Adolphe Kégresse in 1939. However, this inventor lacked the funds to turn his idea into reality. It wasn't until the 1950s that a British car company started to build the first such gearboxes based on two electromagnetic clutches, analogue electronics and coils! In the 1970s, Porsche began implementing dual-clutch transmissions for racing purposes, and in 2003 Volkswagen began mass-producing them for passenger cars. Today, virtually all major brands have them in their range. In Seat, Skoda and Volkswagen it comes under the name DSG. In Audi it is S tronic. Popular names in cars from other brands include EDC, SST, DCT, TCT, DCT, PowerShift, Drivelogic or PDK. TotalEnergies reminds you of the basic principles of their operation and also points out what properties the oils for their service must have.
Ground-breaking technology
Just when it seemed that there would be nothing new on the automatic transmission market, dual clutch transmissions (DCT) made their debut. Their design is based on the use of two clutches instead of one. The first clutch is responsible for the odd gear shaft and the second clutch for the even gear shaft. The entire system is controlled by a gearbox controller. When the driver starts the engine, 1st gear is engaged by the first clutch when the accelerator pedal is pressed and the second clutch is disengaged. While driving in 1st gear, the 2nd gear on the second shaft is synchronised. When a predetermined speed is reached, the controller disengages the first clutch and engages the second clutch, allowing driving in 2nd gear. When driving in 2nd gear, the 3rd gear on the first shaft is already synchronised and ready to be engaged via the first clutch. The pattern repeats itself up to the highest gear. This transmission solution enables very smooth driving and, most importantly, lower fuel consumption compared to a classic automatic transmission with a torque clutch and a system of parallel planetary gears.
Two types of gearbox dominate the market - the first is equipped with a wet clutch assembly (usually 6-speed). The oldest version was the DQ250 used by Volkswagen, with a torque capacity of 350 Nm. The second type is dry clutch transmissions. These usually have 7 gears and work with engines with weaker performance and lower torque. The oldest representative of this group was the DQ200, presented in 2008 (also by Volkswagen), adapted to engines generating torque of not more than 250 Nm (in comparison, the top dual-clutch transmissions with wet clutches withstand torques twice as high).
Robustness, operation and handling
Dual-clutch transmission service companies agree that their service life is between approximately 150,000 and 300,000 km. A lot depends here not only on the design of the gearbox itself, but also on the way it is used and the lubricants applied. Interestingly, some drivers claim that their gearboxes work reliably for more mileage than this, but this is due to... misconception and a lack of comparison with a fully operational car. Some signs of wear and tear progress very slowly, so drivers do not notice them and, over time, assume that "this is the way it is supposed to be". This causes unpleasant surprises when selling the car. The seller declares the car to be fully operational, but in reality it is ready for a major repair, because the gearbox "drags" the gear changes, reacts with a long delay, jerks, etc.
Disregarding servicing in the case of dual-clutch transmissions (as well as other automatics) is due to the fact that such servicing is expensive. Servicing, regardless of its type, after a mileage of about 200,000 km may cost, for example, PLN 5,000.
TotalEnergies oils for dual-clutch transmissions
Oil change intervals are always specified by the manufacturer. It is important to strictly adhere to the operating instructions in such matters. Only where no relevant data are available can average values be used. In the case of dual-clutch transmissions with wet clutches, we can assume an interval of 60 to 150,000 km. In gearboxes with dry clutches, the oil generally works for life under light operating conditions. When driving almost continuously in city traffic, an oil change after approx. 150,000 km or 10 years may be recommended.
The main requirements for dual-clutch gearbox oils with wet clutches are optimum frictional properties for clutches and synchronisers, compatibility with the friction materials of wet clutches, protection of synchronisers. In such gearboxes, the oil has contradictory tasks to fulfil. To reduce the friction coefficient on the gears and, by using special additives, to increase the dynamic and coefficient static friction on wet clutches.
Dual-clutch transmissions with dry clutches can be ioverlooked in this case, as they place similar demands on the oil as classic manual transmissions.
TotalEnergies FLUIDMATIC DCT MV
TotalEnergies offers special oils for dual-clutch transmissions with wet clutches. An example is FLUIDMATIC DCT MV. It is a gear oil made with synthetic technology, designed for dual-clutch "wet" gearboxes to ensure their proper operation. The product provides very good protection against wear even under heavy loads and has good compatibility with sealing materials. Thanks to its parameters, it is suitable for the majority of wet double-clutch transmissions available on the market.
The use of a dual-clutch automatic transmission enables smooth gear changes and, most importantly, lower fuel consumption compared to a classic automatic transmission with a torque converter and a system of parallel planetary gears. If you have a car with such a gearbox, you must take care of it and remember to use the right dedicated oil for this type of gearbox and change it regularly. Piotr Karkocha, Technical Department, TotalEnergies Marketing Polska.