Transmission Fluid Change Guide [2023]

Transmission fluid change is an important routine maintenance practice. It must be done when it's due for the car transmission—manual or automatic—to function optimally. You have probably read or heard people talk about other car fluids like brake fluid and air conditioning refrigerant. they all require routine change. This further stresses the importance of transmission fluid change.

transmission fluid change

An expert will take you through an easy step-by-step process to perform a transmission fluid change in this article. Also, this article will explain other important topics and concepts around transmission fluid. From its function to the types. Some pressing questions will also be answered. But to do that effectively, we will need to start from the beginning. What’s a car transmission? What’s transmission fluid?

What's a car transmission?

car transmission

The different car components have to efficiently work together for the internal combustion engine to run smoothly. The transmission is one of the most important components of a car engine. To put it simply, a car transmission is the gearbox of every automobile. The gearbox employs gears and gear trains to produce speed and torque conversions from the car engine. It subsequently transfers it to the car wheels.

Modern-day vehicles come with two types of transmissions: manual and automatic. Before the advent of automatic transmissions in the 1940s, manual transmissions ruled the automobile industry. Nowadays, however, automatic transmissions are standard in modern vehicles. Read more about manual and automatic transmission here.

What's transmission fluid?

transmission fluid change

Generally, many different fluids run through the various components of your vehicle. Some of them include radiator fluid, engine oil, water, and air conditioning refrigerant. All these fluids must be kept in check for the car to remain in good working condition.

Like these aforementioned fluids, transmission fluid is essential. Transmission fluid helps to lubricate a car's transmission components. This is how it maintains consistent optimum performance. As such, transmission fluid change is just as important as changing your car's engine oil.  

Types of transmission fluids

Your car's transmission is either manual or automatic. Different fluids go into the two different car transmissions. As you might have guessed, automatic transmissions use automatic transmission fluid (ATF). The precise use of ATC is dependent on your car's transmission technology. Manual transmissions, on the other hand, use manual transmission fluids.

They are a variety of oils that come with API specification GL-4. Note: Always check your owner's manual to make sure you're putting the right fluid into your car’s transmission.  

Functions of transmission fluid

The main function of transmission fluids is the lubrication of the sub-components, such as the bearings, of the transmission. However, transmission fluid can serve other purposes as well. These secondary functions are as follows:

  • Transmission fluid cleans and prevents the wear of metal parts and surfaces.
  • It helps to reduce high operating temperatures as well as perform cooling fiction. Transmission fluid increases the operating range of the temperature.  
  • Transmission fluid aids the increase of the engine's rotational speed.
  • It generates friction and hydraulic pressure in automatic transmission vehicles. This enables the internal parts to work well.
  • Transmission fluids allow cars to shift gears with ease, preventing the wearing down of the parts.

Note: Transmission fluid comes in different types and qualities. Do well to refer to your owner’s manual when choosing fluids to use. Also, an ASE-certified mechanic can help identify the right one for your transmission fluid change.

Transmission fluid change: a step by step guide

transmission fluid change

The process of transmission fluid change is not complicated. If anything, it's straightforward and easy to do. However, it can quickly get messy and cumbersome. You may have to prepare your mind for that possibility before you start.

The following are the steps you need to follow to successfully change your transmission fluid:

Step 1

The first thing to do while performing a transmission fluid change is to start your car and let it idle for a couple of minutes. The goal is to get the engine to an operating temperature. Draining transmission is easier and more efficient at operating temperature. Once you've achieved the desired temperature, turn off your ignition.

Step 2

Now, raise the front of your car and secure it. Place a two-gallon catch pan (or something larger) on a tarp, newspaper, or cardboard. Then, loosen the bolts from only one side of the transmission pan.

transmission oil change

Note: Be mindful of hot exhaust fluid and parts.

Step 3

Now, carefully loosen the bolts on the other side of the exhaust pan. At this point, the pan will tilt and commence draining. When you complete loosening the bolts, remove and lower the pan. Drain the remaining fluid into the catch pan.

Step 4

Break the gasket seal as gently as possible on this next step of transmission fluid change. Use a screwdriver if you need to. Move to clean the surfaces of the gasket on both the loosened pan and the transmission housing. Inspect the pan for internal damage and wipe it off with solvent.

Step 5

Remove the old O-ring and transmission filter. You will want to keep the drain pan under it since the filter contains fluid. Then, replace them with a new O-ring and transmission filter respectively. Note: Make sure that the O-ring fits well in its designated orifice.

Step 6

Now, you will affix the new gasket to the pan. Avoid using gasket sealer or adhesive for the attachment, instead, use oil-soluble grease.

Step 7

Confirm with your owner's manual about using thread sealer on some of all of the bolts of the transmission pan. Once you're done with that, use your fingers to screw all the fasteners.

Step 8

Torque the bolts of the pan to spec spirally. Start at the center. The maximum torque is typically around 13 pounds per foot.

Step 9

Now will be the time to lower your vehicle. Then, replace the transmission fluid with the recommended amount. Again, refer to your owner's manual to confirm.

Step 10

This is the last stage in the transmission fluid change process. The bulk of the work is done but you need to do one last check. Turn on the car's ignition, warm it up for a while, and turn it off. Check for leaks. If you get nothing, try one more thing. Turn on the car engine, run it up to operating temperature on even ground. Take the shifter across all gears and park the car. Now, check the dipstick as the engine idles.

Note: Practice good safety behaviors throughout the transmission fluid change process. Use recommended personal protective gear, including goggles, helmets, safety gloves, and shoes. You will be preventing injuries by doing so.

How often should you carry out transmission fluid change?

Even though car transmissions are built to work at high temperatures, consistent overheating can damage the fluid. This will often necessitate transmission fluid change. The rule of thumb is to change your transmission fluid for every 30,000 to 60,000 miles traveled. However, you should check your owner's manual to confirm the recommended change intervals.

Difference between transmission fluid change and transmission flush

A transmission fluid change will just replace most of the old fluid with the new fluid. On the other hand, a transmission flush makes sure no old fluid is left in the transmission, torque converter, and cooler lines by the time the new one is coming in.

Can you top up the transmission fluid?

Yeah, you can top up the transmission fluid. But you must first read the fluid level correctly. Only ad a cup at a time and reread level. Make sure you don't overfill or use unrecommended fluid.

What happens if the transmission fluid is low?

low transmission fluid

Your transmission fluid level must be at the proper level at all times. Otherwise, you may face expensive repairs. Low transmission oil will wear down transmission components, leading to the eventual breakdown of the vehicle. The following are some of the signs to watch out for when your transmission fluid is low:

  • Changing gears will be considerably difficult. Often, it may not respond at all. This issue is worse in automatic transmission.
  • There will be oil drip or puddle underneath your car, an indication that the transmission fluid is leaking.
  • The changing of transmission fluid color from a light, clear color (mostly red) to a darker, muddier color.
  • Your car may shudder or shake.
  • Your engine will roar weirdly when it's accelerating or going around a bend.
  • You may also perceive a slight burning smell.
  • Low transmission fluid will lead to gear slippage. This is because your car will be unable to produce the much-needed hydraulic pressure. The issue can spill onto impacting the ability of the engine to accelerate.
  • Modern-day vehicles come with the technology that indicates if the transmission malfunctions. You will see it on the dashboard.

Note: Allowing low transmission fluid to longer will result in extensive and expensive repairs. Always keep an eye on your transmission fluid level. Perform a transmission fluid change when it's due and without delay.


Transmission fluid change may not be as popular as an engine oil change, but it's just as important. It must be done when it's due of the transmission must continue to deliver power to the car wheel. More importantly, it should be done properly. The whole process has been highlighted in this article. If you're not sure you can pull it off, take it to a trusted technician.

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