How to Flush Transmission Fluid (2024)

Understanding Transmission Fluid

Your vehicle’s transmission is responsible for smoothly operating the gears and transferring power from the engine to the wheels. Transmission fluid plays a pivotal role in this process by lubricating moving parts, reducing friction, and dissipating heat generated during operation. Often, its main role is as a hydraulic fluid for solenoids and valves.

Over time, however, transmission fluid can degrade, leading to diminished performance and potential damage to the transmission system. Knowing when to address your transmission fluid is essential for maintaining your vehicle’s longevity. Keep an eye out for warning signs such as:

  • Unusual noises – Grinding or clunking sounds may indicate insufficient lubrication.
  • Slipping gears – If your vehicle unexpectedly changes gears or has difficulty staying in gear, it could be a sign of inadequate fluid levels or quality.
  • Delayed or harsh shifting – A sluggish or rough transition between gears can signal the need for a transmission fluid flush.
  • Burnt smell – A burnt odor emanating from the transmission fluid suggests overheating, indicating a need for immediate attention.

DIY Transmission Fluid Flush

Before you start the transmission fluid flush, gather the following tools and materials:

  • Jack and jack stands
  • Wrenches and sockets
  • Oil drain pan
  • Funnel
  • New transmission fluid
  • Filter kit (if applicable)

With all of your equipment and parts on hand, begin the process of changing your transmission fluid. These are broad strokes that you can follow, but your vehicle might have other nuances, so follow the manufacturer’s processes.

As with any car repair, work safely. Ensure the vehicle is on a level surface, apply the parking brake, and wear safety gear, including gloves and eye protection.

Step 1: Locate the Transmission Cooler Inlet Hose

Refer to your vehicle’s manual to find the transmission cooler hose. Place the oil drain pan beneath it. Also, in preparation, have your transmission fluid containers opened and close by.

Step 2: Drain the Old Fluid and Flush the System

Disconnect the transmission cooler line that enters the radiator with hot fluid. With a thin funnel in the dipstick tube, start the engine and begin pouring the clean fluid into the funnel. As it’s going in, old fluid is being pumped out of the cooler line into your drain pan, flushing contaminants from the system. Use eight to ten quarts to complete the flush, then shut the engine off.

Step 3: Remove the Pan

If your vehicle has a removable transmission pan, remove it to access the transmission filter. Replace the filter if needed.

Step 4: Clean the Pan

Clean the pan thoroughly to remove any debris or residue. If it isn’t completely clean, it may not seal properly and could leak.

Step 5: Install the New Filter

If applicable, install the new transmission filter according to the instructions provided in the filter kit.

Step 6: Replace the Pan

Securely reattach the transmission pan. Seal it with the required gasket or with a silicone rubber adhesive sealant. Torque the bolts according to the manufacturer’s spec.

Step 7: Refill with New Fluid

Using your funnel, add the recommended amount of new transmission fluid. Refer to your vehicle’s manual for the correct type and quantity.

Step 8: Start the Engine

With your foot on the brake, start the engine and move the shifter through each gear. Allow the engine to run for a few minutes to circulate the fluid.

Step 9: Check the Fluid Level

While the engine is running, check the transmission fluid level and top up if necessary.

Step 10: Test Drive

Take your vehicle for a short test drive to ensure smooth shifting and optimal performance.

Choosing the Right Transmission Fluid

Choosing the right transmission fluid is crucial for your vehicle’s transmission system’s health. Using the wrong type of fluid can lead to poor performance, increased wear and tear, and potential damage.To identify the right fluid:

  • Refer to your vehicle’s manual to identify the specific type and viscosity of transmission fluid recommended by the manufacturer.
  • AutoZone staff are knowledgeable and can assist you in selecting the correct transmission fluid for your vehicle.
  • Extreme temperatures, towing, or heavy-duty use may require a different type of transmission fluid. Take your driving habits into account when making a selection.

Frequency of Transmission Fluid Flush

Regular transmission fluid maintenance is essential for optimal performance. As a general guideline, consider flushing your transmission fluid every 30,000 to 60,000 miles. However, check your vehicle’s manual for manufacturer-specific recommendations. Factors could affect the interval including:

  • Driving conditions – Heavy-duty use such as towing or stop-and-go traffic may require more frequent fluid changes.
  • Vehicle age – Older vehicles may require more frequent fluid changes to compensate for natural wear and tear.
  • Manufacturer recommendations – Always follow the guidelines provided in your vehicle’s manual for the most accurate maintenance schedule.

Common Transmission Fluid Issues and Solutions

Certain conditions are common for transmission fluid. These tips can help you work through your situation.

  • Low fluid level – Top up the fluid to the recommended level immediately to prevent damage to the transmission.
  • Contaminated fluid – If the fluid appears discolored or has a burnt smell, it may indicate internal issues. You might need to talk to a professional for further inspection.
  • Slipping gears – Address this issue promptly by checking and adjusting the fluid levels.

If you find unusual debris during the flush, a more in-depth inspection of your transmission system is going to be necessary. You might need a rebuild or replacement. Address any leaks promptly by tightening connections or replacing faulty seals.

By following these DIY transmission fluid flush instructions and tips, you can ensure your transmission’s longevity and performance. Regular maintenance not only extends the life of your vehicle but also contributes to a smoother and safer driving experience.

Whether you need transmission fluid or repair parts, AutoZone has everything you need along with trustworthy advice to get the job done right.

FAQ/People Also Ask

How often should I flush my transmission fluid?

It is generally recommended to flush your transmission fluid every 30,000 to 60,000 miles, but consult your vehicle’s manual for manufacturer-specific guidelines.

Can I use any transmission fluid for my vehicle?

No, it’s crucial to use the specific transmission fluid recommended in your vehicle’s manual to ensure optimal performance and prevent potential damage.

What are the signs that my transmission fluid needs attention?

Signs include unusual noises, slipping gears, delayed or rough shifting, and a burnt smell emanating from the transmission fluid.

Is flushing transmission fluid something I can do at home?

Yes, flushing transmission fluid is a DIY task that can be done at home with the right tools, materials, and instructions.

Are there any risks associated with not flushing transmission fluid regularly?

Yes, neglecting regular transmission fluid maintenance can lead to decreased performance, increased wear and tear, and potential transmission system damage over time.

How to Flush Transmission Fluid (2024)


Can you flush a transmission yourself? ›

Disconnect the transmission cooler line that enters the radiator with hot fluid. With a thin funnel in the dipstick tube, start the engine and begin pouring the clean fluid into the funnel. As it's going in, old fluid is being pumped out of the cooler line into your drain pan, flushing contaminants from the system.

Is it better to flush or drain transmission fluid? ›

With a flush, all the old fluid is removed by a flush machine and replaced with new fluid, allowing for optimal transmission performance. A fluid change is a drain-and-refill, with some old fluid remains in the transmission after the change, which can contaminate the new fluid — and diminish performance.

What is needed for a transmission fluid flush? ›

The first thing you need is a transmission filter service kit. The service kit includes a transmission filter and a pan gasket. You're also going to need a catch pan and 3 to 6 quarts (3 to 6 liters) of automatic transmission fluid. All transmission fluid varies from car to car.

How much should a transmission flush cost? ›

Drivers can expect to pay $125 to $250 for a transmission fluid flush service. This is approximately twice as much as a transmission fluid change. This is due in large part to the additional fluid required. A flush will take 12 to 22 quarts, while a fluid change requires 5 to 7 quarts.

What is the downside of transmission flush? ›

A theory here is that flushing can dislodge debris that's trapped in some of the internal passages, allowing it to clog up other passages downstream. It could also blow out old seals that are otherwise doing their job.

How many hours does it take to flush a transmission? ›

How long does it take to flush a transmission? A trained mechanic can perform a simple transmission flush in three to four hours using a commercial flushing machine or pump inlet. A transmission fluid change takes just about 30 minutes.

What happens if you never flush transmission? ›

The main thing that happens if you don't change your transmission fluid is that the system can overheat and cause a system failure. Low transmission fluid can also delay or cause difficulty in shifting, which can prevent your vehicle from accelerating or operating correctly.

Does your car run better after a transmission flush? ›

After a transmission fluid flush, you may notice that your vehicle shifts smoother, and that your transmission operates better than before.

Will a transmission flush fix hard shifting? ›

Can an automatic transmission fluid flush fix a transmission which is shifting poorly? The answer is yes; sometimes. While we only recommend a transmission flush as a maintenance service to prolong the life of this costly component, sometimes a flush will improve how your transmission operates.

How many years does transmission fluid last? ›

Automatic: Every 60,000 to 100,000 miles

If you drive manual, most manufacturers will recommend changing your transmission fluid every 30,000 to 60,000 miles. If you have automatic, you can typically boost that range up to 60,000 to 100,000 miles. There's no harm in changing your fluid early.

How to tell if transmission fluid is low? ›

In the meantime, it's a good idea to familiarize yourself with the tell-tale signs that you may be low on transmission fluid.
  1. Noises. ...
  2. Burning Smell. ...
  3. Transmission Leaks. ...
  4. Slipping Gears. ...
  5. Slow Gear Engagement. ...
  6. Vehicle Accelerates Poorly. ...
  7. Check Engine or Transmission Warning Light Is On.

How do I know if my car needs a transmission flush? ›

Signs You Need A Transmission Flush

Other than the obvious check engine light, if you observe slipping gears, transmission whine, delayed shifting, or poor acceleration, then you might want to consider having the transmission fluid changed or perhaps even flushed.

Which is better transmission flush or change? ›

Then, new fluid is added to ensure optimal transmission performance. Flushing your transmission fluid is a better, more thorough alternative to a basic change, which, of course, means it will also cost you more. However, just because it is the better option, doesn't mean it is what you need to do every time.

Can I change transmission fluid myself? ›

Changing transmission oil yourself can save you money and prevent you from waiting for an appointment with a mechanic. However, it can be a messy and dirty job, so always contact a professional transmission specialist if you have any doubts.

Can you drain transmission fluid at home? ›

Locate the transmission fluid pan.

Examine the pan. In most vehicles, you'll be able to drain the transmission fluid by removing a drain plug in the center of the pan and letting the fluid drain out into a receptacle. On some vehicles, however, you might have to remove the transmission pan entirely.

Can you flush water out of an automatic transmission? ›

Usually, some amount of water will come out of suspension and form white gummy masses in various areas of the unit. This is why the unit cannot be flushed to remove all of the water. In addition, the presence of water will start rust forming on the ferrous metal parts throughout the unit.

Can I add transmission fluid without flushing? ›

While you may be able to get by with a simple transmission fluid change instead of a full flush when you need a quick fix, it won't protect your transmission for too long. Meaning it is not the best way to ensure the longevity of your vehicle. That is why you need a complete fluid flush and replacement.

How to get air out of transmission fluid? ›

Loosen the bleeder valve and pull a vacuum with the pump. You will need to use the catch can that comes with most vacuum pumps to catch the fluid. When all the air bubbles are gone then the system is bled. This may take a while so keep check of the amount of fluid in the reservoir and do not let it run out.

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