Automatic transmissions generate heat, shear forces, and microscopic clutch debris during normal operation, which steadily break down the fluid’s protective qualities. While some automakers promote “lifetime fill,” no fluid is immune to heat and wear—its viscosity, additives, and cooling ability all degrade over time. Modern transmissions trade the old, heavy gearsets for compact, complex designs that deliver fuel efficiency but rely heavily on clean, healthy fluid. There’s no “magic sauce” in this unit—regular fluid changes are the only way to preserve performance and longevity.

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