Chrysler began a limited development program directed toward a new automatic transmission fluid (ATF) early in 1989 and launched a full time effort in 1994. The development process for the new ATF involved a significant level of bench testing and eventually vehicle tests to evaluate the durability and shift quality of the ATF. The bench tests included those that pertain to oxidation and shear stability, anti-wear, frictional properties and torque converter shudder. Vehicle tests were primarily extended durability in both internal vehicle fleets and at external taxi sites. The mileage accumulated in this phase of the development program exceeded two million miles, all with no fluid drains out to 100,000 miles. Additionally, shift feel tests were conducted in Chrysler vehicles to verify compliance to targets. This paper summarizes the tests and results that lead to the development of the new Chrysler fill-for-life automatic transmission fluid.