- The quantity of fluid within any transmission is measured with the transmission's dipstick, which extends into the transmission's pan. The dipstick can provide an accurate reading only if the fluid within the pan is even, meaning that the fluid is distributed evenly within the pan. To ensure that the fluid within the pan is evenly distributed, make sure the vehicle is positioned on a level surface.
- When the vehicle is being operated, the transmission fluid actually circulates within the transmission. If you take the fluid measurement while the transmission is cold, the vast majority of the fluid will have actually collected at the bottom of the pan, and the result will be a false reading. There is an even greater risk when measuring the fluid level of an automatic transmission, which uses a torque converter rather than a clutch. A large portion of automatic transmission fluid is actually stored within the torque converter. Therefore, to ensure that the quantity of fluid is measured accurately, first allow the engine to idle until it is warm. Once the engine is warm, the transmission should be shifted through its gears several times to ensure that the fluid has circulated throughout the transmission.
- Check the amount of fluid within the transmission only while the engine is idling, after having been first allowed to reach normal operating temperature. Take the measurement at the transmission's dipstick, which, for most vehicles, is located on the passenger's side of the vehicle between the transmission and the engine block. Withdraw the dipstick, then wipe it down and insert the dipstick back into the transmission. When an engine is first started, the fluid within the transmission tends to splash around for a second or two, which can result in a false fluid reading because the fluid can actually reach a higher point on the dipstick as it splashes. Withdraw the dipstick for a second time and look for the marks that have been stamped into the end of the dipstick. Most dipsticks have stamps that read "Full" and "Add," while other dipsticks instead read "Hot" and "Cold." The fluid level should be just under either the "Full" or "Hot" mark. If the fluid level is lower that the mark, you must add fluid.
- Adding transmission fluid is fairly straightforward, but there is a risk of adding too much fluid. If you overfill the transmission, the additional fluid can create enough pressure to blow the seals within the transmission. Therefore, the keys to adding the correct amount of transmission fluid are adding fluid only in small increments and monitoring the tip of the dipstick. Withdraw the dipstick from the transmission, then insert a funnel into the dipstick tube. Pour the fluid into the transmission via the funnel until the fluid level on the dipstick reaches just under the "Full" or "Hot" mark, depending on the dipstick.
