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1 800 255 4417 www.castrol.com/GPS Transmission Fluids Background & Properties July 2017 Types of Transmissions and Diagnosing Problems Automatic Transmissions An automatic transmission uses electronically- or hydraulically-controlled friction clutches to select gears. Although easier to operate, automatic transmissions sometimes require more maintenance. Automatic transmissions typically require an automatic transmission fluid. Premium automatic transmission fluids (ATFs) are designed to: • Prevent metal-to-metal contact and wear; • Promote efficiency in vane pumps, planetary gear sets and bushings; • Maximize fuel economy; • Allow low temperature operation; • Control oxidation to guard against oil thickening; • Provide correct frictional properties for shifting clutches; • Be compatible with seals; and • Protect against thermal degradation. Diagnosing Automatic Transmission Problems Problems associated with automatic transmissions can sometimes be traced back to the fluid. Using a TO-4 fluid in an automatic transmission will result in harsh shifts, poor low temperature performance, mediocre transmission response, sludge and deposit formation and copper and bronze corrosion. Using a tractor fluid in an automatic transmission will often cause burnt shifting clutches, elongated shifts, inadequate holding capabilities and sludge and deposit formation. An automatic transmission operating with an improper fluid will increase the likelihood of shortened component life, unscheduled downtime and elevated maintenance costs. Fluid choices for automatic transmissions should take into account severity of service, ambient and operating temperatures, which will influence viscosity grade selection, and any OEM-required approvals. For example, Allison prefers a TES-295 fluid for severe or extended service automatic transmissions, a TES-353 fluid for its more severe, off-highway automatic transmissions and a TES-389 fluid for its lighter duty and standard service, on-highway automatic transmissions. Once the fluid type and grade is established, choosing a quality ATF will enhance transmission performance and component life while decreasing costly downtime. Powershift Transmissions The powershift transmission has some internal components similar to that of the automatic transmission, but with some key additions. The control of the powershift transmission is manual and allows for a wide range of speed ratios with an almost instant shift from forward to reverse. Most powershift transmission fluids have evolved from motor oil and multi-viscosity recommendations to straight weight TO-4 transmission fluids. This fundamental shift in fluid type was prompted by the design of the powershift transmission itself. Today's powershift transmissions have highly sensitive friction-based components that require a "grabby," not slippery, fluid to achieve a tight lock-up. D 6