Car encyclopedia

Automatic Transmission Fluid

Automatic transmission fluid is a lightweight oil that is used to operate the hydraulic mechanisms in an automatic transmission, provide lubrication, and act as a coolant for the transmission. When new, it's usually a cranberry red color.

Symptoms of Wear or Failure

  • Rough shifting
  • Delayed shifting

Related Repair Advice

  • It is critical to use the correct fluid type when adding or servicing the automatic transmission fluid
  • We recommend changing the transmission fluid every 30,000 to 40,000 miles under normal conditions. If the transmission has a filter, that should be replaced as well. If you operate your vehicle under severe conditions (e.g. extreme weather, towing, or a lot of stop-and-go traffic), the transmission should be serviced every 20,000 to 30,000 miles.
  • Your repair shop may recommend a transmission fluid flush, which will require up to 16 quarts of transmission fluid. This will increase the parts and labor price when compared to a normal drain and fill of the transmission.
  • Not servicing the transmission fluid at the recommended interval can result in extremely degraded fluid. Servicing a transmission with high mileage and extremely degraded fluid can result in shifting issues after the service. The clean fluid can actually remove varnish build in the valve body. As a result, one or more valves many not seal as well as before the service.

Ask a Question Find a Shop
Featured Articles
Ask a Question