Transmission fluid is used to cool and lubricate the internal components of the transmission as well as to enable the transmission to shift gears. Over time, the chemical properties of the fluid begin to break down, thereby reducing its ability to lubricate and cool the transmission. A proper fluid amount is also vital to the longevity of the transmission. A fluid level which is too low can result in erratic shifting and high temperatures. A fluid level which is too high carries the risk of premature transmission failure. Maintaining a proper transmission fluid level in a truck is therefore important, particularly if the truck is used for towing.
Park the truck on a level surface.
Start the truck's engine and allow it to reach normal operating temperature.
Open the truck's hood while allowing the engine to idle and withdraw the transmission's dipstick from the dipstick tube. The transmission's dipstick tube is usually located on the passenger's side of the engine and rests next to the firewall.
Read the marks at the tip of the dipstick to determine the fluid level. There are two marks on the dipstick. One mark typically reads "Hot" and the other "Cold." Some dipsticks instead read "Full" and "Add." The fluid level should be just under the "Hot" or "Full" mark.
Add additional transmission fluid if necessary by pouring the fluid directly into the transmission's dipstick tube.
