Some Physical Effects of Transmission Fluid Degradation

Laboratory studies using bench, chemical and dynamometer tests were carried out to define some of the ways in which fluid degradation may occur and affect the serviceable life of an automatic transmission, as well as how components, individually or in combination, may accelerate or retard fluid degradation. Once these details were defined, the test results indicated two major conclusions. First, degradation products of an automatic transmission fluid (acids, sludges, varnish forming products, and so on) should be considered as new fluid components, since they may have more effect on transmission performance than the original components. And secondly, retention of desirable friction control properties must be a prime consideration in the design of a satisfactory automatic transmission fluid.