fluid’s electrical conductivity. Most fluids are noted to have a conductivity level between 0.9 S/cm and 8*10-9 S/cm at 100°C which qualifies it as an insulator [6].

Dual Clutch Transmissions (DCT) are rising in the market and generating more interest. DCT are different than AT in that it uses clutch plates, like a manual transmission, rather than relying on a torque converter [7]. While the gears can swap automatically, there is also an option to use paddle shifters to manually shift the gears giving it more versatility [7]. AT is explicitly the simpler and more convenient option, but there are an ever-growing band of enthusiasts who prefer DCT because they want more control of their gear changes. Compared to AT, DCT are efficient because they use fewer mechanical components and slipping elements and has a high degree of freedom regarding gear ratios [8]. The salient benefit of DCT is that it improves fuel economy which entices OEMs to drive production [8]. There are two types of DCTs: wet and dry clutch [8]. Dry clutch systems have a lower torque application with smaller engines and requires Manual Transmission Fluids (MTF) [8]. Wet clutch systems have a higher torque application and require enhanced DCT Fluid (DCTF) which combines both gear protection quality of MTF and clutch friction control of ATF [8]. Wet clutch is divided into two designs: single sump for lubricating both gear and clutch or a separate sump for each [8]. Single sump designs are increasing in popularity, but the fluid needs to be explicitly designed for it to complement both the gear and clutch. Separate sumps involve using DCTF for clutch and MTF for gear box for optimal performance. A challenge to note is the need to limit shuddering when shifting gears while providing a high torque capacity. A well-balanced fluid will need to be formulated in order to achieve these goals in the future. Overall, DCTs are growing and are forecasted to grow higher than AT by 2024 which strongly emphasises fluid development for this type of transmission.



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While DCT are expected to dominate the market for performance vehicles, continuous variable transmissions (CVT) are foreseen to remain popular for small automotive markets [9]. CVT is an automatic transmission that utilises a pair of variable width pulleys rather than gears for smooth acceleration [10]. Unlike AT, CVT allows for an infinite number of gear ratios and can allow operation at the optimum power band [10]. With that said, CVT is seen to only be viable for small cars with four-cylinder engines due to the difficulty of retaining optimal power at higher loads. Other than limited power capabilities, the relevant disadvantage of CVT is the absence of the gear shifting sensation which changes the experience of driving and is unnerving for some drivers. CVT drivers described the feeling to be “rubber band” like and perceives constant slipping of the transmission [9]. However, overlooking the unorthodox sensation aspect, CVT is economically more affordable than DCT and is viewed to advocate simplicity when driving, which suits comfortably for non-intuitive drivers. Also, CVTs are expected to improve in their fuel economy while operating at optimal speeds.

CVTs may also aid the engine reliability and longevity since the engine is operating at an optimal and essentially constant engine speed (RPMs).

Currently, CVT uses CVT fluids which are more complex than ordinary ATFs and are more specific in their applications. CVT fluid is formulated with full-synthetic, premium-based oils, friction modifiers, anti-wear additives, and shear stability modifiers to improve oil lifetime [11]. While ATFs focus primarily on friction control to alleviate resistance in the gears, CVT fluids are formulated to advocate friction to prevent the belts from slipping on the pulley system. Since CVT fluids are applicable for a smaller niche of transmissions, its future lies on the level of dominance of DCT and whether consumers can adjust and accept the eccentric sensation of the transmission.

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