Eventually the clutches burn out and the transmission calls it quits. At higher temperatures the transmission begins to slip, which only aggravates overheating even more. If the temperature gets above 250 degrees F., rubber seals begin to harden, which leads to leaks and pressure losses. As heat destroys the fluid's lubricating qualities and friction characteristics, varnish begins to form on internal parts (such as the valve body) which interferes with the operation of the transmission. And once that happens, the trouble begins.Īt elevated operating temperatures, ATF oxidizes, turns brown and takes on a smell like burnt toast. The problem is even normal driving can push fluid temperatures well beyond safe limits. But if the fluid temperature goes much higher, the life of the fluid begins to plummet. If fluid temperatures can be held to 175 degrees F., ATF will last almost indefinitely - say up to 100,000 miles.
Normal driving will raise fluid temperatures to 175 degrees F., which is the usual temperature range at which most fluids are designed to operate. It doesn't take long for the automatic transmission fluid (ATF) to heat up once the vehicle is in motion. Why ATF Wears OutĪn automatic transmission creates a lot of internal heat through friction: the friction of the fluid churning inside the torque converter, friction created when the clutch plates engage, and the normal friction created by gears and bearings carrying their loads. For optimum protection, change the Transmission Fluid and filter every 30,000 miles (unless you have a new vehicle that is filled with Dexron III ATF, which is supposed to be good for 100,000 miles). That's why transmission shops are making a fortune replacing burned out automatic transmissions.
#How to install transmission oil cooler 2004 impala manuals
Most owner's manuals say it isn't necessary. Change transmission fluid every 30,000 miles.