How to Check and Add Transmission Fluid To Your Car

Even if you aren’t too interested in cars or don’t keep up with your vehicle’s maintenance that regularly, you probably still know that it’s pretty important to check your engine oil on a regular basis.

What most people forget about, though, is the importance of checking their transmission fluid.

Oil is responsible for more than just helping your vehicle’s engine operate smoothly. Your vehicle’s transmission also needs to be able to shift properly, be correctly lubricated, and stay cool.

After all, without this in place, your vehicle has no way of moving forward or backward.

Man with dirty hands funneling transmission fluid into the car

In the sections that follow, we’ll be taking a closer look at why it’s so important to check your transmission fluid every time you go in for an engine oil change, as well as everything you need to know about how to do so.

The good news? You won’t have to do this task nearly as much as you have to change your car’s engine oil, but that’s not an excuse to slack off and not make sure it’s healthy on a routine basis.

What Does Transmission Fluid Do? And Why is it Important to Check it?

First and foremost, it helps your vehicle move. Unlike a manual transmission, an automatic one uses a fluid coupling to match the speed of the engine with the rotation of the wheels via the transmission when you put your vehicle in drive.

The fluid flows through all the various parts of a torque converter, using incredible pressure to connect and disconnect the engine from the transmission.

Just like engine oil, it also lubricates and cools all the gears located within the transmission.

If this fluid becomes old and worn out, its lubrication qualities wear out, it breaks down, and small shards will actually accumulate inside as time goes on.

When Should I Check My Car’s Transmission Fluid?

We have an entire article dedicated to how often you should change transmission fluid, but below are the main points and advice:

During Oil Changes

A good practice would be to do a check each and every time you have its oil changes.

If you’re worried about this adding to what already seems to be a daunting to-do list, don’t be! It doesn’t take more than a few seconds to run a check.

For most vehicles, the transmission fluid dipstick is under the hood with the oil dipstick.

Not Shifting Gears Properly

Another good time to run a check would be if your vehicle starts behaving strangely when shifting into a different gear, perhaps not shifiting smoothly, or jerking while accelerating.

If your transmission is holding on to gears longer than it should, is shifting abruptly, or is not shifting at all, this isn’t always a reason to panic.

The first thing you should do in such cases is to check the transmission fluid level. If it’s running low, you can try adding some and possibly save yourself from an expensive trip to the mechanic.

Leaks Underneath The Vehicle

If you notice that there’s something leaking underneath your vehicle when you move it, you should also run a check.

If it’s low, your transmission could be leaking, and you will need to take action to rectify the problem as soon as possible. This is especially the case if you can’t find the leak by yourself.

How Do I Know When I Need To Add In?

Running a check on the fluid on a regular basis makes you more familiar with what “normal” and “abnormal” looks like, as well as what the appropriate levels should be.

Additionally, the transmission fluid dipstick is clearly labeled to show the maximum and minimum levels that must be present for everything to function properly.

If it’s running below the recommended minimum level, you need to add more.

What Do I Need to Do To Run a Check?

Prepare Yourself With Tools And Materials

Similarly to checking your vehicle’s oil, you shouldn’t need any special tools, but you will need a cloth with which to wipe the dipstick after it’s drawn.

A white cloth or paper towel is best for this task, as transmission fluid has a reddish-pink color and using a light-colored cloth may skew how it looks.

Park The Vehicle And Warm It Up

Once you’ve prepared yourself and have all the materials you need by your side, it’s time to prepare the vehicle itself.

First things first, find a level area on which to park and allow the vehicle to idle for about 15-20 minutes. You may also choose to take a ride around the block if you would rather not let it sit.

If you’ve been out driving already, you can check the fluid as soon as you park your vehicle, as it will already be warmed.

Examine It

Once you have your cloth and the vehicle is warmed appropriately, you will have to leave the vehicle running, open the hood, and locate the dipstick.

The exact location of the transmission dipstick will be outlined in your owner’s manual and will vary depending on the make, model, and drive layout of the vehicle.

Once you find it, pull the dipstick out of its housing tube, wipe the dipstick entirely, and replace it.

Once replaced, remove the dipstick again. Instead of wiping it off this time, place the end of the dipstick on your cloth or rag and examine the fluid clinging to it.

Pulling the dipstick twice is crucial for an accurate reading. Idling and driving cause fluid shifts and will circulate around the dipstick, causing the appearance of higher levels. Re-dipping the dipstick will render an accurate and precise measurement of the fluid and its makeup.

What Should I Be Looking For?

What’s The Level?

The end of the transmission dipstick will have markings signifying a high and low level or a “hot” and “cold” level.

If the fluid is under the lowest level, you will need to add more.

What Does It Look Like?

Fresh, healthy transmission fluid is usually clear pink to reddish in color. With that being said, certain types are green, but that isn’t normally the case.

Generally speaking, the darker it looks like in color, the dirtier and older it is. This means that it has broken down over time and needs to be replaced as soon as possible.

Dark brown, milky, sludgy, or even black color is a sign that it’s burnt, and there may also be a problem from a leak or even transmission damage.

What Does It Smell Like?

New transmission fluid doesn’t necessarily smell like anything special in particular, but old one often has a burnt smell that you can notice pretty easily.

If your fluid smells odd or burnt, it has most likely deteriorated and needs to be changed as soon as possible.

Keep An Eye Out For Particulates

There should not be any kind of particulates found in there.

Dark brown, opaque fluid is caused by the moving parts of the transmission slowly breaking down over time. Particulates can often be seen in vehicles which haven’t had their transmission fluid changed or flushed at all during their lifetime.

This is a clear sign of wear and tear, as well as potential damage. A mechanic should be consulted if particles or pieces of metal are found on the dipstick.

How Do You Add Transmission Fluid To Your Vehicle?

This is a fairly simple task that requires only a few tools and little expertise. Don’t worry about having to go to a professional to do this for you, as that’s not obligatory.

What Will I Need?

To do this task, you will need:

  • A rag or paper towel, preferably one that you don’t mind getting dirty
  • A funnel, which is helpful but not entirely necessary
  • The replacement transmission fluid itself
  • Gloves aren’t necessary, but can be used as well if you prefer

Be sure to read your owner’s manual first for the exact kind of transmission fluid your vehicle requires.

As technology improves, vehicles are becoming more and more sensitive to specific manufacturer requirements, and using the wrong type could result in significant damage requiring possible replacement of its components.

What’s The Process Like?

Gauge How Much You Will Need

Because every vehicle is different, each will have a specified amount of fluid it can hold.

If you are simply adding some in rather than replacing all of it, be sure to do so slowly and in intervals, checking the levels periodically via the same method initially used.

Overfilling can cause damage and leaking, neither of which are fun to deal with. So, it’s imperative that only the appropriate amount be added – not too much, and not too little.

Place The Funnel And Pour It In

A funnel will make this job easier.

Once it is placed over the dipstick housing tube, pour away, making sure to still check the levels periodically to prevent overfilling.

Wipe Off Spills And Residual Fluid From Other Components

Once you have filled the chamber to the appropriate level, make sure to clean up any spills that might have occurred.

Fluid that has spilled on the engine or other components underneath the hood could cause the area to smoke and even possibly start a fire, should the fluid become too hot.

Leave The Engine Running For A Minute Or Two Longer

Once everything has been added and cleaned, leave the vehicle running for a few more minutes to allow the fluid to circulate through the transmission and reach all the necessary crevices so as to prevent damage.

If you still have some questions, here’s a useful video we believe will answer anything that might not have been covered in the above sections.

Anything Else I Need To Know About?

Check Your Owner’s Manual First

Some vehicles, especially Hondas, don’t require the vehicle to be running in order to check the transmission fluid – but will require the fluid to be checked shortly after the vehicle is turned off.  For this reason, always remember to check your owner’s manual first to see if your vehicle needs to be running or not.

A Note About Electric Vehicles

Electric vehicles don’t have transmissions as we know them. They use a single gear, and because they just stop moving when the vehicle stops moving, they don’t idle, having no need for a transmission that disconnects the drive shafts to the idling engine.

So, for those of you who have an electric vehicle, you won’t have to worry about transmission fluid.

A Note About Manual Vehicles

Vehicles with a manual transmission are usually a little different than automatics, in the sense that some don’t have a dipstick in the engine bay. Oftentimes, because of the way a manual transmission is designed, there is a plug to check the fluid underneath the vehicle.

Technological Advances

Nowadays, not checking the transmission fluid is becoming the norm. As technology and car parts become more advanced, more manufacturers are completely sealing the transmission, eliminating the need to run checks on your part and add anything in.

Unfortunately, this also means that if there is a problem with the transmission, a mechanic will have to perform the required maintenance for you. It also means that if the problem is serious enough, a complete transmission overhaul might be in order.

The Importance Of Flushes

Lastly, a transmission fluid flush is often more beneficial than just adding some in and calling it a day.

If you’re losing transmission fluid, chances are that there is a leak. If the leak is bad enough, serious repairs may be needed and a total flush might be necessary to fix all the issues.

You can always consult your owner’s manual concerning any of these issues, or ask a certified mechanic to help you if you don’t feel like handling this on your own.

Wrapping it Up

It may not seem as important a task as checking the oil or inflating the tires properly, but running these checks regularly and adding some in should your vehicle need it is helpful in preventing any unwanted issues that could arise.

Transmission repair costs are among the most costly repairs that a vehicle could encounter, with some total replacements costing upwards of $10,000. Running checks on a regular basis is a very small price to pay to make sure the consistency and levels are correct.

And, if you’re worried about any of this being too complicated for you to handle, don’t be! Nowadays, most cars are designed to allow you to check all of this without having to pull anything apart or dig around sensitive engine components that you’re not comfortable working with.

Anybody can check their transmission fluid and add some if needed, including even the most novice drivers.

Shawn Furman

I've had a passion for cars since 8 years old, and been a subscriber to Auto Week magazine since my 10th birthday. Ever since I turned old enough to drive, I have driven as many vehicles as possible, while teaching myself how to perform maintenance and upgrade work on every vehicle I've owned. For the past 10 years, I've been honing my skills as a vehicle hobbyist, in recent years also enjoying writing car reviews, opinion articles, vehicle how-tos, car-buying guides, and even provide individual consultations for those who need car-buying advice. In addition to writing for Vehicle Scene, I currently write for Autolist, and also own and operate my own vehicle blog website, The Unlimited Driver.

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