How to Change Transmission Fluid? A Step-by-Step DIY Guide

Like so many other things in your vehicle, fluids wear out with time and use and need to be changed.

Changing transmission fluid is a bit messier than just changing your oil, and tends to involve more steps. However, if you have the space and can follow simple instructions, you may be able to save a few bucks by doing it yourself.

If you don’t have the space to change the transmission fluid at your home or you aren’t comfortable doing it yourself, then you can have a mechanic do it for you instead. They can even do a transmission fluid flush, something that is much more difficult than a simple change.

For now, though, let’s look at everything you need to know about how to change transmission fluid by yourself.

What Tools Will You Need to Change Transmission Fluid Yourself?

The first part of any do-it-yourself project is to gather the necessary equipment to help you get the job done. The following list discusses what items you will need to change your transmission fluid on your own.

• Rags: Almost anytime you do something with your vehicle, you will get dirty – and be warned, this can be a particularly dirty job! The more rags you can have at your disposal, the better off you will be.
• Your Owner’s Manual: Your owner’s manual is your instruction guide for everything you will need and all the steps you’ll have to take. It will also highlight some very important “dos” and “don’ts” during the process.
• A Funnel or Oil Pump: After your old transmission fluid is drained, you will have to replace it. You’ll need a funnel if you have a vehicle with an automatic transmission. Much like motor oil, there will be an opening under your hood, sealed with a dipstick in which you can pour new fluid (don’t confuse this with the oil dipstick!). 

If your vehicle has a manual transmission, you will most likely have to pump gear oil or transmission fluid back into the transmission through a plug on top of the housing.

• Jack: Regardless of whether your vehicle has a manual or automatic transmission, you will have to jack up the front part of your vehicle to crawl underneath and release the transmission pan or drain plug.
• Jack Stands or Wheel Ramps: After you have jacked the vehicle up, you will need a way to keep it there for the duration of the change. If you have wheel ramps, you will simply need to drive the vehicle onto the ramps, put the emergency brake on, and chock the rear wheels.

You can also use jack stands for this purpose. If you decide to do that, here’s a guide we put together about how to use jack stands, as well as another guide we wrote about some of the best jack stands out there for vehicle-related work.

• Wheel Chocks: While the vehicle is jacked up in the front, you should use wheel chocks for the non-lifted end of the vehicle as an added safety precaution. This will ensure the vehicle stays stationary while you are underneath it.
• A Towel or Some Other Kind of Tarp: Because this can be such a messy process, you should lay down a towel or tarp to prevent any spilled fluid from getting into the surrounding environment.
• A Large Oil Catch Pan: Transmission fluid is considered to be hazardous. You will need to collect the old fluid in a large catch or drain pan and take the used fluid to be recycled. A wide catch pan is recommended to catch as much fluid as possible.
• Torque Wrench or Ratchet: To drain the transmission fluid, you will need to unbolt the catch pan in an automatic transmission, or release the drain plug in a manual transmission vehicle. Both will probably require a good bit of force to loosen and tighten when you are finished.
• Gloves: Just like rags, gloves are always helpful during any messy automotive maintenance job. Unlike rags, though, gloves will protect your hands from getting burned by falling transmission fluid, as draining works best when the engine has been running and the fluid is hot.
• Cleaning Solvent: Once the transmission pan is taken off, it is a good idea to clean it out, as small bits of debris might build up on the bottom. Water can cause parts damage from oxidation, so a cleaning solvent or specifically engineered transmission cleaner is necessary.
• Screwdriver: When the pan is finally unbolted or the drain plug unscrewed, there could be an old gasket or seal that keeps holding the removable part in place. If this happens, a screwdriver can be used to gently pry off the pan.
• New Gaskets: Once a pan or bolt is removed from the transmission, it is always a good idea to replace the gasket which was previously used to seal everything. Gaskets and seals are often the first parts of any vehicle to go bad because they are made from rubber and plastic rather than metal.
• Transmission Fluid: This task wouldn’t be complete without the actual transmission fluid. Make sure you check your owner’s manual to see what kind your vehicle requires and have a look at this article to find out what some of the best transmission fluids of today are.

How to Change Transmission Fluid: A Step-by-Step Guide

The change process in and of itself is not all that complicated, but it is usually cumbersome and messy. Let’s look at what you will need to do to perform one properly.

1. Bring the Vehicle to Normal Operating Temperature

Most fluids flow easier when they are warm. Transmission fluids are the same, therefore it will flow easier (and more fluid will be drained) when it is warmer. You can warm the transmission by idling the vehicle for a few minutes, or by driving around the block.

2. Jack the Vehicle up and Secure It

You will need to access the transmission pan or drain plug from underneath the vehicle.

Use a jack to raise the front of the vehicle, use jack stands or wheel ramps to keep the vehicle raised, and chock the rear wheels to make sure the car doesn’t inadvertently move while you are working.

3. Loosen the Transmission Pan in an Automatic or Drain Plug in a Manual Transmission to Drain

Once you locate the pan (if you have automatic transmission fluid), or the drain plug (if you have a manual transmission vehicle), you will need to remove it.

Place your fluid drain pan underneath the pan or plug, then use your torque wrench or ratchet to unscrew the pan or drain plug.

Once the pan or plug is removed, align your fluid catch can so that as little fluid as possible leaks out. If your vehicle has a transmission pan, unscrew one side slightly more than the other so that the fluid has a more concentrated flow.

4. Remove the Transmission Pan and Clean With Cleaning Solvent

When most of the fluid drains and the flow rate is reduced, you can fully remove the pan. Most manual transmission vehicles don’t have a removable pan.

Once the pan is removed, check it for unwanted debris. If you see metal shavings, you may have transmission damage and should consult a mechanic – you may have to replace the entire transmission fluid pan. Otherwise, the pan should be free of foreign material.

You should always clean the pan or plug with cleaning solvent before replacing it after the fluid has completely drained. Both transmission pans and plugs are magnetized to catch any foreign metal that would otherwise get caught in the transmission gears and cause extensive damage.

5. Install the Transmission Fluid Filter

Many transmissions have filters in them, much like oil filters. These should also be replaced to make sure no leftover material is transmitted into the new fluid.

6. Replace the Transmission Pan Gasket and Pan or the Filler Plug Seal

Once the remaining fluid is drained, you will need to replace the pan or drain plug to prevent the new fluid from leaking.

Replace the gaskets of the pan or o-ring on the plug to form a protective seal, and apply a layer of grease to each gasket, further preventing the possibility of future leaks. Use grease to line the gaskets or o-ring plug seal rather than sealant, though sealant can be used if grease is unavailable.

7. Refill the Transmission Fluid

Refer to your owner’s manual to see how much transmission fluid your vehicle holds.

For automatic transmissions, use the funnel to pour the necessary amount of new transmission fluid into the filler reservoir under your hood.

For manual transmissions, an oil pump is usually needed to pump new gear oil into a hole on the top of the transmission housing.

8. Turn the Vehicle on and Let It Idle

After the fresh transmission fluid is added, turn your vehicle on and allow it to idle.

This will allow the new fluid to circulate throughout the transmission housing and coat all gears and bearings.

9. Check the Fluid Levels

In an automatic vehicle, you can check the transmission fluid level while it is idling by pulling the transmission fluid dipstick. Add more fluid if necessary.

In a manual transmission vehicle, you will have to turn the vehicle off.

Your owner’s manual will detail how to check transmission fluid levels, but normally you can check it by placing your finger into the filler hole to see if any fluid gets onto your finger.

10. Check for Any Leaking

After you have added fluid and checked fluid levels, examine the areas around and underneath the vehicle for any leaking. If you have one, head to a mechanic – you don’t want to be driving around with low transmission fluid.

11. Test the Transmission

If there is no leaking, lower the vehicle from its stands, get inside, and test the transmission by shifting through several gears.

If the vehicle shifts correctly, the job has been successfully completed.

For more useful information that could come in very handy, watch this video.

Why Should You Change the Transmission Fluid Yourself?

The most obvious reason to do this yourself is to cut down on the costs involved in hiring a mechanic to do it for you. Parts are often more expensive at a mechanic shop or dealer, and you will have to pay more for labor. If you are concerned about costs, it is worth doing this all on your own.

Some manufacturers suggest performing this task once every 30,000 to 60,000 miles, especially if you frequently travel in stop-and-go traffic or consistently tow with your vehicle.

If you enjoy learning new skills and working with your own two hands, then you’ll get great satisfaction out of changing the transmission fluid yourself, as it’s slightly more involved than just changing your engine oil. If you’re unsure about the frequency you can check out our article on how often you should change transmission fluid in your car.

Where Should You Go If You Don’t Want to or Can’t Replace Transmission Fluid Yourself?

Any dealer or mechanic shop will be able to perform this task should you not have the space, the confidence, or the tools necessary to do it yourself at home.

As an added bonus, shops will also be able to perform a transmission flush for you while at it, which is much harder to do by yourself than just a fluid change. This can be very beneficial, but you should know that it isn’t always necessary.

How Much Will a Transmission Fluid Change Cost?

Most transmission fluid changes at a dealer, shop, or auto parts stores will cost between $80 and $250, with an added flush costing much more.

If you choose to do it yourself, you will only need to buy the fluid and filter, provided you already have all the necessary tools. If you don’t have the tools, however, it may cost about the same as a shop if you have to buy vehicle jacks, wheel chocks, etc.

Are There Any Other Tips I Should Know About?

Many of the newest vehicles come equipped with sealed transmissions and “lifetime”, no-change fluid, which allows you to skip transmission service altogether. To find out if this applies to your vehicle, consult your owner’s manual.

Also check your owner’s manual for any special information about how to change transmission fluid in your vehicle, including the type of gasket sealant or lubricant you should be using.

If you are taking on this task for the first time, you should be able to find transmission fluid change kits. These come with several tools necessary to complete the job.

Last but not least, always remember to replace and re-apply your transmission fluid pan gasket. It is an easy item to forget, but it will prevent leaks and future issues!

Wrapping It Up

Changing your transmission fluid is a very important task that can prevent serious repercussions down the line. Doing it yourself can be rewarding, can save you the hassle of scheduling an appointment, and is very likely to save you some money.

Regardless of what vehicle you have, changing this fluid – if your vehicle allows – is a pretty straightforward task, and knowing how to do it is a great skill to have.

After reading this guide, we hope the process now seems much easier than you first thought!