Automatic transmission fluid
) is the fluid used in vehicles with self shifting or automatic transmissions
. It is typically colored red or green to distinguish it from motor oil
and other fluids in the vehicle. On most vehicles its level is checked with a dipstick
while the engine is running.
The fluid is a highly specialized oil optimized for the special requirements of a transmission, such as valve operation, brake band friction and the torque converter as well as gear lubrication.
ATF is also used as a hydraulic fluid in some power assisted steering
systems, as a lubricant in some 4WD transfer cases
, and in the manual transmissions
of many modern front-wheel drive
Modern ATF typically contains a wide variety of chemical compounds intended to provide the required properties of a particular ATF specification. Most ATFs contain some combination of rust preventatives, anti-foam additives, detergents, dispersants, anti-wear additives, anti-oxidation compounds, surfactants, cold-flow improvers, high-temperature thickeners, gasket conditioners, and petroleum dye.
There are many specifications for ATF, such as the DEXRON
and MERCON series, and the vehicle manufacturer will identify the ATF specification appropriate for each vehicle. The vehicle's owner's manual will typically list the ATF specification(s) that are recommended by the manufacturer.
Automatic transmission fluids have many performance-enhancing chemicals added to the fluid to meet the demands of... Read More