How to Flush Automatic Transmission Oil

Some car owners choose to perform their own minor car repairs instead of paying to have their car serviced by a professional mechanic. Flushing the automatic transmission oil from a car is one of the most common tasks done by a car owner.

Although some people prefer to take their car to an automotive shop to have their transmission oil flushed out, it is something that you can easily do yourself by following a few simple instructions.

1. Set an oil drain pan below the transmission of the car. The pan will catch the oil when the plug is pulled.


2. Remove the drain plug from the transmission. To do this use an adjustable wrench to remove the bolt holding it in place, which is located at the bottom of the transmission’s oil pan.


3. Allow the oil to run out of the transmission. Make sure the oil is running into the drain pan.


4. Remove the oil dipstick from the transmission.


5. Use a funnel to pour the oil in the dipstick tube. If you are unsure of how much fluid you need to add refer to your owner's manual.


6. Disconnect the pressure line from the transmission cooler, which is located on the radiator.


7. Start the engine and allow it to run for about 2 to 3 seconds after disconnecting the line. It will start spurting out fluid.


8. Place a rubber fuel line onto the spurting line and place the other end of the rubber line in the drain pan.


9. Start the car again and the transmission will pump the remaining fluid into the drain pan.


10. Pour new fluid into the tube as the old fluid is being pumped out.


11. Keep flushing the transmission until the fluid coming out turns bright red.