How to Check and Add Oil to an Automatic Transmission

Park the vehicle on a flat surface while keeping the engine running. You may want to quickly shift through each gear before parking.

Lift the hood up. Cars usually have an internal lever used to push the hood, located next to the left hand side of the driver’s seat. See the user manual if you can’t find it.

Find the automatic transmission oil pipe. In many new cars the automatic transmission ramp will be labeled, otherwise check your manual to find it’s location.

• In rear-wheel drive vehicles, the dipstick is located at the back of the engine, above the oil tank.
• In front-wheel drive vehicles, the dipstick is usually located at the front of the engine, connected to the transmission. ^[1] In most cars, it will be to the right of the oil tank.

Lift the oil dipstick from the transmission. Wipe with a clean rag or paper towel, reinsert the rod and lift it out again to check the transmission oil level. The transmission oil level should be between the two markers “Full” and “Extra” or “High” and “Low.”

• Normally, you don’t have to add gear oil. If the oil level drops significantly below the “Extra” and “Low” lines, your system probably has a leak and you will need to have your vehicle repaired.

Check the condition of the gear oil. Good automatic transmission oil is usually red (though sometimes pink or light brown, free of bubbles or odor. If the following appear, have the vehicle repaired.

• If the transmission oil is dirty brown or smells like burnt bread, it means the oil has meaninglessly burned itself and cannot dissipate the heat generated by the transmission. The oil can be checked more closely by placing several clean sheets of paper and waiting for about 30 seconds to see if the oil has splattered. Otherwise, the oil must be changed immediately, or the transmission itself has suffered serious damage.
• If the transmission oil is milky brown, it has been contaminated by the radiator coolant leaking out and entering the automatic transmission’s oil cooler. Get your car repaired right away.
• If the transmission oil foams or bubbles, there is too much oil in the cylinders, or you may be using the wrong type of transmission oil or the engine has a clogged transmission vent.

Add gear oil if needed. Add a little oil at a time, rechecking the oil level periodically, until the oil reaches the correct level.

• When driving for the first time, you will need to add 3.5 to 4.5 liters of transmission oil if you have completely changed the engine and started like new. ^[2] If not, check the dipstick regularly to avoid overfilling the oil trough.

Start the car and, if possible, go through the gears. This process allows the newly poured transmission oil to be recirculated and coat each gear and lubricate it. Start with the vehicle parked and the engine running, if possible, raise the wheels off the ground. Going from One to Three, including Forward, Overspeed and Reverse, stop at each gear for about 1 minute to ensure even oil coverage. Once that’s done, let the engine run for a few more minutes before putting and parking.

Check the dipstick again to determine how much oil you need to add. Check the oil dipstick, because the transmission oil can spray from the oil trough to the gears, if necessary, spray more oil.

Add the required amount of oil to the standard level. Depending on whether you’re just filling up with gear oil or you’re replacing the entire oil trough with new gear oil, you may need to add more oil at this point.

• If you are simply filling with oil, you only need to add about 1 liter or less.
• If you replace the entire oil pan and start like new, you may have to add between 4.5 and 13.5 liters, depending on the make and model.