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You know your car and all of its service costs like the back of your hand. We’re willing to bet that you could tell us the prices of headlights, oil changes, coolant flushes, and even a new set of spark plugs without having to refer to your notes. What about transmission fluid changes?

It’s no secret that transmissions endure plenty of neglect. You’re not the only one to blank out on the costs of routine services or even recall the last time you even had it checked out. To add some confusion to the matter, transmission fluid changes can cost anywhere from less than $100 to several hundred bucks.

Don’t worry. Car Bibles is here to help you get a handle on those costs. We might not be able to tell you exactly what you’ll spend on your own transmission, but we can dive into the factors that make up the final bill. We’re even going to give you some advice on tackling the job yourself.

Ed. Note: This post was updated with all-new text and images on 8/20/2021.

What Does Transmission Fluid Do?

We’re not going to get too much into the science of how transmission fluids work. There are many different transmissions out there, and system functions can be slightly or majorly different. We just want to give you a simple take on fluid function as a whole so you can begin to understand why fluid maintenance is important.

In a manual transmission, transmission fluid functions primarily as a lubricant, as oil does in your engine. In fact, many manual gearboxes simply use gear oil to get the job done. That’s not the case for all, however. Most newer manual gearboxes actually use automatic transmission fluid (ATF) for a few reasons. Primarily, it’s because it reduces drag while still offering desirable wear and rust protection to the gears — as long as the transmission is designed to work with it.

Automatic transmissions make the fluid wear a few hats, however, which is why ATF and ATF variants exist in the first place. ATF functions as a lubricant, hydraulic fluid, and even a coolant, to an extent. An engine could theoretically function for a short stint without oil before overheating and failure, but an automatic transmission could not function without its fluid.

How Much Does It Cost To Change Transmission Fluid?

How much it costs to change transmission fluid depends on the type of transmission you’re working on and whether you’re doing the job yourself. If the transmissions are different, prices can vary greatly from vehicle to vehicle and even in those of the same make and model.

Generally speaking, manual transmissions are much less costly to service. That’s because they only require a few ounces of fluid to function, something around three to five quarts of fluid is typical. Keep in mind, though, that some manual gearboxes use ATF and others use gear oil. So, you need to take the time to figure out exactly what your transmission calls for to get an exact number regarding pricing.

Automatic transmissions are a little more expensive to service because they require a lot more fluid to run correctly. Automatic transmissions will take anywhere from nine to 13 quarts of fluid to fill. On top of that, many older automatics require the fluid filter to be changed as you replace the fluid. So, you need to purchase that along with the gasket for the pan where the filter resides. Again, a little bit of homework is necessary in understanding your exact transmission and what a fluid service will cost you.

According to RepairPal, taking your car in for a transmission fluid change typically costs between $387 and $446 for parts and labor, but this varies depending on the vehicle. 

How Can I Tell if My Fluid Needs To Be Changed?

Transmission fluid takes a serious beating over the years. Between meshing gears, hard abuse, and extreme heat, it will collect debris, break down and need replacing. How often it needs changing depends on a few factors.

Under normal driving conditions, you’ll want to stick to what’s in the owner’s manual. Remember that service requirements depend on the type of transmission you have, and the manufacturer will offer details specific to that unit. In general, manual transmissions will need the fluid to be changed every 30,000 to 60,000 miles, and automatics traditionally call for servicing every 60,000 to 100,000 miles.

If you’re a spirited driver, you’ll likely want to change the fluid a little more frequently. How often you change it really depends on how hard you are on transmissions. If you’re getting on the pedal every so often or are only towing on the weekends, you can still expect to get some decent mileage out of your fluids. If those events are an everyday thing, however, you might wind up changing the fluid much more frequently.

To determine if your fluid needs to be changed, you need to inspect its condition. If you have a dipstick tube on your automatic, pull it out. If the fluid is a dark brown and smells burnt, it’s time to go. The same rule applies to the oil in your manual transmission, only you’ll have to take a sample from the fluid fill hole to get a good reading.

You never want to let the fluid run until it turns black. In that condition, it will break down and lose its ability to function as necessary. When it does, your transmission can take the beating instead of the fluid, and you might wind up with some serious repair costs. There’s a good chance that fresh fluid will correct any of the performance issues you’re experiencing with old fluid in the transmission, but that’s something you don’t want to take a chance on.

Wait, I Don’t Have a Dipstick Tube

For all of those folks screaming at their screens about how we forgot to mention modern sealed transmissions, we thank you for hanging in there before jumping into the comments section to rip us a new one.

The idea behind these units is that they use lifetime fluids and components. You shouldn’t have to replace the fluid for the life of the car, so no expenses were wasted on dipstick tubes or even bodies that you can easily crack open to inspect. On top of that, the owner’s manual might not provide any details about servicing transmission fluid.

Still, you should inspect the fluid from time to time as lifetime fluids are still going to break down. You can do so from the fluid inspection plug on the transmission. Where it is located depends on the exact model, but the concept is simple. You pull the plug to determine both the fluid health and level. If it’s dirty or low, you know it’s time to replace or add fluid.

What To Know About Changing Transmission Fluid Yourself

Material costs are one thing, the price of labor is another. As long as you’re willing to do the work yourself, you might stand to save a couple dollars on fluid changes. That’s exactly why we want to talk a little bit about how to change transmission fluid on your own.

For the purposes of this article, keep in mind that this is still general advice. The process can change greatly depending on the exact model of transmission you have to work with, so you need to do a little homework to identify the exact procedure and necessary tools to get the job done. Our goal is to give you a good idea of what goes into this type of work to help you decide if you’re better off paying a mechanic or if you should roll up your sleeves and get wrenching. 

Safety

You’re going to have to crawl under the vehicle to change the transmission fluid. You’ll also be spending a decent amount of time under there if you’re dropping the pan and changing the filter. Throw in some unfriendly chemicals, and you have some real danger to worry about. Keep these tips in mind before you start the job.

  • Don’t get under the vehicle unless it’s properly secured. Use a set of ramps or a floor jack to safely lift the vehicle. Make sure to secure the wheels and place the vehicle on jack stands before you get anywhere near the undercarriage.
  • Transmission fluid and gear oil aren’t things you want on your bare skin or eyes, so throw on protective gloves and safety glasses.

Gear and Tools

Everything You’ll Need

We don’t know what tools or supplies you have in your shop, so we’re just going to cover the basics. Keep in mind, you need to find out exactly how much and what kind of fluid your transmission calls for before you start the process. The owner’s manual will provide you with this information, and you should follow those details.

Also, we will note that you want to think about how thorough a job you’re looking to do with an automatic before you get started. Sometimes, replacing all of the fluid in an automatic transmission isn’t desirable, as leaving some of the old fluid behind may aid in the function of the transmission. Even so, it’s a good idea to buy more fluid than you think you’ll need to give yourself a bit of a cushion.

How To Change Fluid in Automatic Transmissions

1. Run the vehicle, then raise it.

Letting the vehicle warm up is optional, but it will make it easier for the fluid to drain. After it’s warmed up, raise and secure the vehicle if you don’t have enough ground clearance to work between the wheels. If you do this, stay mindful of hot surfaces while you proceed to the following steps. 

2. Drain old fluid.

This is a step that’s specific to the transmission you’re working with. Some have a drain plug, which will make life easier. Simply place the drain pan underneath the plug and drain it as you would the engine.

If the transmission doesn’t have a drain plug, you will drain it by partially removing the pan. Loosen a few bolts on one side of the pan and break the seal so that the pan sits at a slight angle. This will allow fluid to escape, so make sure that your drain pan is sitting beneath the transmission while you do this. Some cardboard or newspaper beneath the drain pan will help to contain spills.

3. Replace the filter. 

With the transmission drained, you can now remove the pan entirely to access and replace your filter. Again, the exact process can vary from each model, so you need to do the research before probing around here. If the transmission is a sealed unit, you don’t have to worry about this step.

4. Clean the mating surfaces and install your gasket. 

You need to make sure a perfect seal can be obtained after removing your pan. Take the time to make sure that the pan and transmission mating surfaces are perfectly clean. A scraping tool or box cutter might be necessary to remove any gunk stuck to these surfaces—just take care not to damage the surfaces you’re cleaning. Also, take the time to clean out the pan itself to remove any small metal flakes or debris before reinstalling. After they are clean, you can install your new gasket and then the pan.

It’s a good idea to use a torque wrench when installing the pan. The last thing you want is for a leak to form, and one of the best ways to prevent it is simply by ensuring you torque the hardware to spec. Also, be sure to follow the proper tightening sequence. That will also promote a good seal. 

Tightening sequences for pans are generally performed by working in a criss-cross pattern from the centermost bolts and working your way outward until all the bolts have been tightened to spec. However, you may want to read over the suggested routine in a service manual for your exact vehicle or via internet search to be certain of what’s necessary for the transmission you’re working on. 

5. Fill the transmission.

Next, move to fill the transmission with fluid. You aren’t done with the job just yet, but you want to fill the transmission with fluid for the next step to avoid damaging things.

6. Drain the cooler. 

Most automatic transmissions are attached to a cooler or have cooling lines running to the radiator. To make sure the job is done right, you will need to ensure the cooler has good clean fluid in it. One method of doing so is to remove the return line and run it to a catch pan. Start the car, and watch until clean fluid comes out, then cut the power, reattach the line, and top off the transmission.

Alternatively, you can use compressed air. Remove both lines and run the return line into an oil pan. Attach a source of compressed air to the line coming into the cooler and blow through until all fluid is removed. Then reattach the lines, run the vehicle, and top off the fluid.

7. Start the car on level ground.

Next, you will need to start the car. Let it idle, then manually shift it through all of the gears and return it to idle. Check the fluid level with the car running and top off the fluid as necessary but avoid overfilling the transmission. Ensuring the vehicle is on level ground is crucial to cycling fluid properly.

8. Repeat within a week.

If you’ve purchased enough fluid to fill the transmission from dry, you’ll find that you still have some fluid left over. Well, that’s because your torque converter still has old fluid left inside of it. Many folks will call it quits at this point of the job, and that’s usually OK, especially for high-mileage vehicles. If you want to be more thorough, you can repeat the process within a week’s time to ensure the transmission has a totally fresh supply of fluid.

This transmission dipstick looks like a traditional oil dipstick on the top.\

How To Change Fluid in a Manual Transmission

1. Raise the vehicle.

Changing fluid in a manual transmission might be short and sweet, but you still need to crawl under the vehicle. Make sure it’s raised and secured properly before you do.

2. Locate your plugs. 

Take a minute to identify the location of your drain and fill plugs. In any case, the drain plug will be on the lower portion of the transmission. The fill plug might be tucked up into a tight spot, however. Familiarizing yourself with it now will save you a panic attack later.

Coming from experience, it helps to decide how you will fill the transmission at this point. You definitely won’t be able to get a traditional quart bottle in there. A funnel with a long hose that can run from the engine bay to the transmission might suffice, but a fluid transfer pump usually makes life a lot easier.

3. Drain the transmission.

Simply undo the drain plug and let the fluid drain into your catch pan. This is just like changing the oil in your engine, so you can just let gravity do the work for you.

4. Fill the transmission.

Once the transmission is drained, replace the plug and proceed to fill the transmission to spec. If you’re not sure how much the transmission will take, simply fill until the fluid just starts to trickle from the fill hole, and you should be in good shape.

If you are working with an older transmission that takes gear oil, we recommend using a product like the Valvoline Flex Fill SAE 75W-90 Full-Synthetic Gear Oil. This isn’t a sponsored plug. That soft pouch and spout really do make filling the transmission feel effortless. It is something I use on my own vehicles and have come to love. In fact, I keep the empty pouches around and buy gear oil in large containers to refill them for future projects. It’s a good way around the cost per quart. 

Flex Fill gear oil packets make refills much easier. Photo: Hank O’Hop

FAQs on Changing Transmission Fluid

We know you probably have a few questions, and Car Bibles has the answers.

Q. Is changing transmission fluid easy? 

A. Although the difficulty level will vary across platforms, changing transmission fluid isn’t necessarily a hard job to perform. It takes a little longer than replacing engine oil or coolant. But it’s something someone with an intermediate level of knowledge about automotive repairs can easily perform.

Q. Do you really need to change transmission fluid? 

A. Yes, you do need to change the transmission fluid. It collects all kinds of debris and endures heavy heat and usage, so it breaks down over time. Bad fluid will hurt performance and will potentially damage your transmission. It should be changed as called for in the service manual or in even shorter intervals.

Q. Is it ever a bad idea to change transmission fluid? 

A. On high-mileage vehicles, changing transmission fluid may actually hurt performance. This is because some of the clutch material in the fluid will aid in shifting and so on. If that’s the case, you can still change your fluid, just don’t entirely drain the system. Leaving a little bit behind, such as what’s in the torque converter, can be just enough to prolong performance. This is also one of the situations where additives might be necessary.

Q.What’s the difference between draining transmission fluid and flushing transmission fluid?

A. In simple terms, a fluid change only replaces some of the fluid in the transmission. If you follow the steps we’ve discussed, you are only replacing about two-thirds of the fluid in the unit. On the other hand, a flush is a routine that replaces every last drop of transmission fluid. You can somewhat replicate that by changing the fluid once, then again within a week’s time, but a flush is a specialized process that is far more thorough.

Q. Is it better to drain or flush transmission fluid? 

A. That depends on the situation. If the transmission is on a high-mileage vehicle, a simple drain like we walk you through is enough. On relatively new vehicles, a flush may be beneficial as it will prolong the life of the transmission. However, a flush might cause damage, and generally, a basic drain is a preferred method.

Q. How long does a transmission fluid change take? 

A. You can expect this job to take around an hour or better. Again, this is dependent on the model of transmission you have to work with and what steps are necessary. Regardless, you still want to set aside more time than you think you’ll need as this is no job to rush through.

Video 

Eyes are heavy, the brain is fried, and you still probably have a few questions. The video below walks you through the process of changing transmission fluid. It is around 15 minutes long, but you definitely want to know as much as possible before tackling this job yourself. We have you covered.

We don’t know what you have access to nor do we know what transmission you have to work with. Still, we can talk a little about some products for this line of work. We highly recommend you check out the Valvoline Flex Fill SAE 75W-90 Full-Synthetic Gear Oil, TEKTON Half-Inch Drive-Click Torque Wrench, Hopkins FloTool 42003MI 16-Quart Drain Container, RhinoGear RhinoRamps Car Ramp, and the Craftsman 450-Piece Mechanic’s Tool Set.

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