Automatic Transmission Fluid Temperature
Automatic transmission fluid (ATF) has a life of about 100,000 miles at 175oF. At high temperatures, it oxidizes, turns from red to brown and exhibits a burnt smell. In addition to reducing the oil’s lubricating quality, high temperature produces a varnish on internal parts interfering with the operation of the transmission. Above 250oF., rubber seals harden, leading to pressure loss and leaks. Also, the transmission can slip. In the worst cases,
clutches fail and costly repairs result. ATF manufacturers suggest that for every 20oF. increase in operating temperature above 175oF., the life of the fluid is cut in half. Hence at 195oF., oil life will be about 50,000 miles. Above 240oF., it becomes nil.