How Much Transmission Fluid Do I Need? - Vehicle Freak

• Luka Kusic

Updated on September 16, 2022

The transmission consists of a set of gears that turn the power of the engine into usable energy that can make the wheels turn. A transmission case is a sealed unit that needs a fixed amount of fluid

Add too much, and the seals will break and leak under pressure. Add too little, and the gears will start wearing down due to increased friction and generated heat.

The amount of transmission fluid you need depends on your vehicle. There is no specific upper or lower range, as some transmissions take as little as 1 quart of fluid, while the bigger transmissions take up to 13 quarts.

Even though I can’t tell you the exact amount, I can show you how to figure it out, buy the right type of fluid, and top up the transmission fluid if necessary.

How Much Transmission Fluid Does a Car Hold?

The amount of transmission fluid your vehicle needs depends entirely on the make and model. Fortunately, figuring out the amount and type of fluid you need is very simple – all of the data you need is stored in the owner’s manual.

If not, the vehicle manufacturer certainly has a website where you can look it up.

I don’t like general quantity figures because someone may assume they need a certain amount without checking and overfilling the transmission. This is a very serious problem and can lead to a number of issues which we’ll now discuss.

Why Is Too Much Transmission Fluid Bad?

As I’ve mentioned before, the transmission is a sealed unit that converts the turning of the crankshaft into a force that can be applied to the ground. Its proximity to the engine and the movement of the parts will generate some heat, but nowhere at the level that occurs inside the engine block.

Too much transmission fluid “stuffs” the mechanism and causes a number of problems:

• Transmission fluid leaks
• Hard gear shifts
• Noises coming from the transmission
• Transmission overheating
• Slipping transmission

Let’s start with transmission fluid leaks. Again, it comes down to transmission being a sealed unit, and what happens when you overpressure it – it fails at the weakest link, which is the transmission gasket.

It’s quite a serious and expensive problem to fix, as are any problems with the transmission.

Like swimming in the water, overfilling the transmission will put added pressure on the gears, causing hard shifts and even transmission slipping. You’ll also experience noise and a feeling that the vehicle is losing power.

There is such a thing as too much, and when you add too much transmission fluid, you might actually experience overheating.

That’s because the added stress and frothing of the transmission fluid don’t deliver sufficient cooling. Arguably, too much transmission fluid is as bad as too little of it.

Why Is Too Little Transmission Fluid Bad?

Interestingly, the symptoms of lacking transmission fluid are almost the same as those of too much fluid. To figure out which of the two issues you’re having, just check the transmission dipstick. If you don’t know how to do it, don’t worry.

When the transmission lacks fluid, you’ll experience:

• Gear slippage
• Transmission overheating
• Transmission fluid leaks
• Noises coming from the transmission
• Grinding gear shifts

The lack of transmission fluid leads to insufficient lubrication and dissipation of heat. Without adequate lubrication, the gears will grind and wear out significantly faster than they would otherwise.

This symptom is sometimes accompanied by constant noise from the transmission, but always with grinding when shifting gears.

The heat is going to be a serious issue, and the AT temp dashboard light will turn on. Prolonged driving with an overheated transmission can lead to catastrophic failure.

The heat can even warp the components and cause the gaskets to become brittle and leak. All of these symptoms are very common when you lack transmission fluid, so make sure you’ve always got enough.

The Importance of Transmission Fluid & How to Measure It

From the previous sections, you can see just how many things can go wrong when you don’t have the right amount of transmission fluid.

The transmission fluid lubricates the moving parts and dissipates heat, but it also prevents the oxidation of metal parts, which means that the gearbox cannot rust from the inside.

In the engine block, oil is separated from the combustion chambers by the piston rings. The metal expands when heated, so the rings have to adjust to keep the seal complete, but there’s always a microscopic amount of oil seeping into the combustion chamber.

Every engine burns some amount of oil, but the good ones do not consume enough to require topping up between oil changes.

Transmission works differently. It doesn’t generate heat, aside from the contact between moving metal parts. A significant amount of heat that is transferred to the transmission comes from the engine.

Being a sealed unit, transmission should not consume a drop of oil between regularly scheduled changes. Some transmissions even come with a lifetime, service-free fluid.

Still, checking the transmission levels from time to time is not a bad idea. Interestingly enough, a lot of people don’t even know that the transmission has its own dipstick!

This doesn’t come as a surprise, as the dipstick can be out of reach, and certainly not as conveniently placed as the engine oil dipstick.

The process of checking the transmission fluid levels is identical to the engine oil:

1. Turn on the car and let it idle.
2. Pull out the dipstick.
3. Clean it with a piece of cloth.
4. Reinsert the dipstick.
5. Pull it out again, hold it flat and inspect.

Unlike engine oil which needs a certain amount of temperature to be read accurately, transmission fluid can be measured both when hot or cold. The dipstick has two limits based on the fluid temperature, which makes it easy to read.

How to Top Up Transmission Fluid

There are certain jobs I dread, even as an experienced DIY mechanic. Bleeding the brakes is first, opening up the turbocharger is the second, and anything regarding the transmission is the third job I wish I never have to do again.

Why? Because a lot more can go wrong than can go right. Bleeding the brakes incorrectly will cause a loss of braking power and could lead to an accident. Turbo and transmission are just too sensitive for a DIY mechanic to play around with.

My advice is that if you need to top up the transmission fluid, take your car to a professional mechanic first for an inspection. Lack of transmission fluid is not a common occurrence, so it’s likely that the transmission gasket has gone bad.

The second reason why I don’t want you to be topping up, or especially changing transmission fluid is the whole too much or too little problem. There’s less room for error than with engine oil, and the consequences are more serious.

With this (un)necessarily long warning, let’s get into how the job is done, whether you’re topping up or changing the fluid. With the full fluid change, you just need to bleed the system first.

You can never be too cautious when adding more transmission fluid because getting the excess fluid out is going to be a pain to do. That’s why these steps are going to be more detailed than others you may find, but they should also be a lot safer.

Steps to Add Fluid In an Automatic Transmission:

1. Run the car until it’s at operating temperature.
2. Put the transmission in the park gear and let the car idle.
3. Measure the transmission fluid levels.
4. Use the fluid filler to add more fluid through the dipstick hole.
5. Drive the car for a bit and let it shift gears, or shift them manually if possible.
6. Park, let it idle and measure again.
7. Repeat the process if necessary.

Steps to Add Fluid In a Manual Gearbox:

1. Start the car cold and let it idle.
2. Put the shifter into neutral and measure the transmission fluid level.
3. Use the fluid filler to add more fluid through the dipstick hole.
4. Press the clutch, and shift through all the gears, up and down.
5. Return the shifter to neutral, and measure the level again.
6. Repeat the cycle if necessary.

The amount of transmission fluid you’ll need to add depends on how low the level is, but I wouldn’t add more than a fraction of a quart at a time, just to see how much the dipstick moves.

Driving between every change is optional, but I like to recommend it as it lets the fluid move around the transmission better. On a manual, you can shift gears even when idle, which is enough to run it through the motions and move the fluid around.

You can perform the process when the engine is hot or cold regardless of the transmission type, just don’t do it when the engine is partially hot, or it will distort your readings.

How to Extract Transmission Fluid

It’s entirely possible for you to follow all the steps correctly and still add too much transmission fluid. In that case, the fluid filler/extractor will come in extremely handy.

When extracting the excess transmission fluid, you should work on a cold, idling engine. Connect the extension tube to the extractor, and push them down the transmission dipstick hole.

The process is now reverse to topping up – you’d extract out some fluid, measure, and suck out more if necessary.

FAQs

How much transmission fluid do I need if empty?

When your transmission is completely empty, you’ll need anywhere between 1 and 15 quarts of transmission fluid. The range is so massive because of the different transmission types and applications.

A car that uses a 1.0L engine may only need a quart or two of fluid, while a massive V8 needs up to 13 quarts. To find the right amount, check the owner’s manual or ask the dealership for the information.

How many quarts of transmission fluid do I need for a 4-cylinder?

The answer depends entirely on the make and model of your vehicle, but 4-cylinder engines typically need 2 to 6 quarts of ATF.

Will changing transmission fluid help shifting?

It’s not a guarantee, but changing the transmission fluid may help improve shifting speed and smoothness, especially if the old transmission fluid had a lot of miles to it.

Changing the fluid is also the most inexpensive way of trying to solve the issue, as anything else involves disconnecting and pulling out the gearbox, followed by detailed disassembly and inspection.

How often should I change CVT transmission fluid?

CVT transmission may require more frequent changes, with the shortest interval being just 25,000 miles. For most CVT transmission, the range goes up to 50,000 miles at most, but it largely depends on the manufacturer’s recommendation.

Why you should never change transmission fluid?

There’s a notion that changing transmission fluid is a good idea if you’re driving a high-mileage car. Personally, I do not know enough about this to tell you whether it’s correct or not.

The best thing to do is to change the fluid in regularly-scheduled intervals, and let a professional do it. Some vehicles have maintenance-free transmissions that require no fluid changes, so there are certain vehicles that run the same fluid until they break.

What does slipping transmission feel like?

When transmission slips, you’ll experience a lack of power and a slow response to the gas applied. This happens because the engine is running normally, but the gears aren’t fully transferring the power to the wheels.

What happens if you don’t change CVT fluid?

The answer is pretty obvious – the fluid that is now past its expiration date will change in viscosity, and all the grime it’s collected over time will flow through the system.

Not changing the CVT fluid when necessary is a certain way to save a couple of hundred dollars, only to pay a couple thousand for transmission repairs later on.

Should I change my transmission fluid after 100k miles?

Not necessarily. The 100k miles is a high number, but if your car’s transmission was made with a lifetime fluid, you won’t have to change it at all.

Can you mix old and new transmission fluid?

Yes, because you have to mix new and old transmission fluid when topping up and that’s completely fine. What’s not okay is mixing different types of transmission fluid, as the different chemical compositions may have unexpected side effects.

How long should transmission fluid last?

The durability of transmission fluid depends on the manufacturer and type of transmission. The continuously variable transmission (CVT) generally has the shortest fluid lifespan, but for other types, it can last up to 10 years or even longer.

How much does a transmission fluid flush cost?

The proper transmission fluid change can cost you up to $250 with the fluid included. It’s considerably more expensive than an engine oil change, but it also occurs less frequently and it is a more complicated process.

How many quarts of transmission fluid do I need for a V6?

Transmission mated to a V6 engine uses between 5 and 9 quarts of transmission fluid.

Will transmission problems throw a code?

The transmission will definitely throw a code if there’s a problem and one of the transmission-related dashboard warning lights will turn on, along with the check engine light. There are hundreds of transmission-related codes, with some being manufacturer-specific:

• U1000
• U0101
• U0402
• P0218
• P0700 to P999
• P1702+
• P1800+
• P2700+

How much transmission fluid does a Toyota Corolla need?

Even when we narrow down the question to a specific make and model, without the model year and engine code, we cannot say for sure how much transmission a car needs. Toyota Corolla needs anywhere from 2 to 6 quarts of transmission fluid depending on the powertrain.

How much transmission fluid does a torque converter hold?

The amount of transmission fluid contained by the torque converter depends on its size. A 12″ converter takes 4 quarts, and an 11″ converter takes 3.5 quarts, while a 10″ converter takes 3 quarts of fluid.

How many quarts of transmission fluid do I need for an 8-cylinder?

The transmissions paired with 8-cylinder engines typically use 9 to 13 quarts of transmission fluid.

How much transmission fluid is too much?

The transmission designs that allow for fuel top-ups also have dipsticks to measure the amount of fluid in the system. The dipstick has two measuring points – one for hot and one for cold fluid, so you can measure at the engine’s operating temperature or when the engine is completely cool.

Don’t exceed the limit marked on the dipstick, and you can be sure you don’t have too much transmission fluid.

How do I find my transmission code?

Like any other issue with the vehicle, the transmission codes can be read with the OBD-2 scanner. This inexpensive tool will allow you to read and wipe codes – simply connect it to the OBD-2 port in your vehicle, found in the center console or underneath the steering wheel.

Does the VIN number tell you what transmission you have?

Yes, you can use the VIN number to identify a lot of mechanical components of your vehicle: the transmission, engine, suspension, fuel tank size, brake rotor size, etc.

It’s a really convenient tool and there are some great free VIN checkers out there, so you don’t have to pay for Carfax and other premium options.

Is it OK to slightly overfill transmission fluid?

The transmission has a certain tolerance to the fluid quantity, so you may get away with slightly more transmission fluid if you add too much by accident. However, you should never intentionally overfill the transmission, as too much fluid will lead to a number of problems.

Summary

As you can see, there is no definitive answer to the question of how much transmission fluid your car needs. We can’t even determine the approximate amount – it all depends on the powertrain of your vehicle.

The owner’s guide, manufacturer’s website, or the unofficial information found online can tell you what transmission your vehicle has. From there, it’s easy to determine how much transmission fluid you need, and I’ve explained in depth how to top up or change the fluid, although I wouldn’t recommend it.

Here are some other related topics you may want to read:

Bubbles In Transmission Fluid: What You Should Know

Can Too Much Transmission Fluid Cause Slipping?

How Long Can a Car Run Without Transmission Fluid?