The transmission fluid needs to be changed from time to time in order to extend the life of the transmission, usually every 100,000km (check your car manual for more details). When the transmission fluid is old you can have trouble traveling, or your car can become sluggish or stall. You can consult the machine manual to find out how often the fluid needs to be changed, but you can also learn how to diagnose and fix the problem yourself.
Steps
Method 1 of 3: Get started
Step 1. Check the transmission fluid level first with the dipstick
ATF fluid is used in automatic transmissions. It is usually colored green or red to distinguish it from engine oil and other car fluids. In most vehicles you can check the level with the dipstick while the engine is running.
- Look for the dipstick of the transmission fluid, it usually has a red handle. It should be clearly labeled and easily accessible on most cars, close to the oil one. The temples have a hot and a cold reading. If your engine hasn't been running in the past hour and you don't live in extremely hot weather, consult the cold reading for appropriate levels.
- If the levels are low, but the liquid looks clean, you could simply refill the system. If the liquid appears discolored or dirty, it needs to be changed. If you are at the mileage that requires changing the transmission fluid, change it anyway even if it looks good.
Step 2. Lift and support the vehicle with jack stands
Make sure you have enough room to go under the vehicle, and check that the jack stands are securely supported.
Always park flat when working under the car and use jacks, jack stands or other support systems for added safety and to prevent the car from sliding off the supports
Step 3. Find the gear oil tank
The pan will be attached to the bottom of the transmission, with 6-8 bolts; to find it you will have to crawl under the car. For front-wheel drive vehicles, the transmission is usually located left to right under the engine compartment. In rear-wheel drive vehicles it is generally located under the center console area facing from front to rear.
- Check the tank. In most vehicles it is possible to drain the gearbox oil thanks to a drain plug located in the center of the tank, letting the fluid come out and collecting it in a container. On some vehicles, however, it may be necessary to remove the transmission pan entirely. The liquid pan will have several smaller bolts around the edge to hold it in place; you will have to unscrew them to extract it.
- If you want to inspect the oil filter, gaskets, or any other component, it is recommended that you remove the pan anyway to examine the assembly more thoroughly.
Method 2 of 3: Drain the Liquid
Step 1. Place a drip tray under the drain hole
To catch the falling gear oil you will need to put a container large enough to collect it under the drain bolt. Cheap plastic containers are available at most auto shops.
If your transmission does not have a drain plug, draining the fluid is a very dirty operation. Since the fluid will drain around the pan (rather than through the drain plug hole), you'll need a sump at least as wide as the drive pan itself to avoid making a mess
Step 2. Drain the liquid
To drain the liquid, you can either unscrew the drain bolt or remove the bowl and the liquid will start draining right away. Chances are you will get some liquid on your hands (it's almost impossible to avoid), but you can make sure to keep your face and chest shielded to minimize spillage. Put the bowl in place, unscrew the cap, pull it off and quickly move away.
- If the transmission pan has a drain plug, remove the cap to drain the fluid into a drain pan. Use a container that can hold up to ten liters of gear oil, although most likely there won't be that much.
- If you need to remove the entire transmission tray, unscrew the two upper bolts in half, and then completely unscrew the others. As soon as the last bolt is unscrewed, the tray will begin to drip and the liquid will begin to flow down. To free it you may have to use a little force.
Step 3. Examine the liquid that comes out
Most automatic gearbox trays have a magnet inside to collect metal shavings that have been produced by the worn moving parts. Remove these too, along with the rest of the liquid left inside. It is normal for there to be metal shavings: they represent the typical wear of gears. Large or irregularly shaped pieces, however, are not normal. Keep them aside and ask for advice from an experienced mechanic who can tell you if the gearbox doesn't need special attention.
About 50 percent of the fluid will remain in the transmission when you drain it. To remove all fluid, including that in the torque converter, you must completely drain the transmission, a process that is usually part of a more comprehensive maintenance routine
Method 3 of 3: Replace the Liquid
Step 1. Evaluate the transmission oil filter and gaskets
As you change the fluid, it is a good idea to check and evaluate the condition of the filter and seals and replace them if necessary. You don't need to change them every time, but cracked or leaking filters and gaskets must be removed and replaced with identical parts that you can buy at an auto supply store. To find out which pieces you need, ask the shopkeeper for advice.
Whether you do this or not, replace the bowl and drain plug assembly by tightening with a socket wrench or ratchet. Do not overtighten the bolts
Step 2. Add the new gear oil
Once the pan is back on the vehicle you can put the car off the kickstands and replace the transmission oil with the appropriate type. There are several types of transmission fluid, so be sure to use the type recommended by the manufacturer. Check your car's manual and add the recommended liquid.
On most vehicles, transmission fluid is added through the port from which the dipstick was removed. In most cases the new fluid passes directly through this opening. You will need to use a funnel. Pour a little less liquid than you have drained, so as not to overfill. You can find the correct quantity in the car manual
Step 3. Turn on the machine and let it run for a few minutes
Turn it off and check the liquid level. If it's low, add more. Repeat this until the liquid is at the right level. Avoid overfilling.
Step 4. Dispose of the liquid properly
Transmission fluid is harmful to nature, and it is important to avoid discharging it into the environment. Always wear gloves and wash them to remove any residue immediately after completing the fluid change.
Most auto parts stores and bodyshops have a liquid recycling program that allows them to store engine oils, transmission fluids, and other vehicle fluids that collect during vehicle maintenance. Find a collection site in your area
Advice
Find a liquid collection center before starting the change. Think about how to transport the old dirty liquid. Protect the environment
Warnings
- Manual transmission requires a different procedure for changing transmission fluid. This wikiHow is for automatic transmissions.
- Replacing the transmission fluid can extend the life of your transmission even if the fluid is still red when you check it by pulling out the dipstick. If the liquid is red or dark brown in color and smells like burning, the transmission should be completely drained. There can be significant damage to the transmission.
