How To Check and Change Your Prius Transmission Fluid

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A hybrid car is a great automobile to have, and a Toyota Prius is one of the best. A popular reason for owning one of these vehicles is the low maintenance they require. That being said, some care needs to be taken, such as regularly checking your transmission fluid and changing it when necessary.

Did you know changing Prius transmission fluid is just as important as changing your oil? And many people forget about it.

The transmission fluid in your Prius is important for the well-being of your car. Replacing it at certain intervals is equally important. Today, you will learn how to check your transmission fluid, as well as when and how to change it.

Prius Transmission Fluid Check

Transmission fluid is important for all cars. One of the easiest ways to check the level is by going under the hood and manually checking it. 

That being said, all Toyota Prius’ have a sealed transmission meaning there is no dipstick. While your transmission fluid should be somewhat maintenance-free, if you feel the need to check it, there will be a check valve under the transmission. 

This valve will allow you to check the color of the fluid. Bright red-ish pink means it is in good condition. Dark red-ish brown means it is old and should be changed. The fill plug can also be checked. When there is a sufficient amount of fluid in your Prius, you will see it drip out of the fill plug.

It’s important to note that the vehicle needs to be completely level to check the fluids, so you may be better off taking it to a mechanic to check, as they can keep it level on a hydraulic lift.

When To Change Transmission Fluid

There is some debate about the Prius transmission fluid change interval. Toyota, for example, indicates that the transaxle (transmission) fluid in these models is a “lifetime” fluid. Unfortunately, that is false. 

As a general rule of thumb, you should check the levels every 30K miles and change your Prius transmission fluid at intervals of 60k and 90k miles. 

How To Tell Your Toyota Prius Transmission Fluid Needs to be Changed

There are a few ways to tell whether or not you need a fluid change. The first, as mentioned, is mileage. 

The second indication is the “maintenance required” light on your dashboard. This light will illuminate when your transmission levels are low and when you need an oil change.

Keep in mind that the light comes on every 5,000 miles indicating an oil change is needed. You won’t always have a low transmission fluid level at this time.

Another indication is when your hybrid starts behaving oddly. Take a look at some physical signs:

  • Revving to high RPM at low speeds
  • Revving high when going uphill
  • High transmission temperature
  • Car won’t move at all 

If you see physical signs of distress, some damage has usually occurred already.

How To Change Your Prius Transmission Fluid

Performing a Prius transmission fluid change is not as complicated as you might think, but it can be expensive. Professional mechanics can charge upwards of $300 for this task, however, if you’re not comfortable working on your own vehicle, a professional would be the best route to ensure nothing goes wrong. 

Each Prius model is more or less the same when it comes to a transmission change. 

If you’re choosing to do it yourself, to start, you will need to gather some basic supplies:

  • Ramps, jack, or lift
  • Torque wrench
  • Socket wrench
  • 24mm socket head
  • 10mm hex socket
  • Drain pan
  • 1 or 5-gallon bucket
  • Funnel with extension hose
  • Toyota ATF WS transmission fluid (4 quarts)
  • 2 gasket washers (crush washers)
  • Dropcloth or newspaper
  • Oil pan

Once you have all of your supplies, follow the easy steps below.

Lift The Car

First, you will need to use ramps, a jack, or a lift to raise your car off the ground. This allows you to work under the car easily. 

You can use two ramps or a jack, but it is better to have the car level. Four ramps or a lift is preferable, but you can do it with a jack if need be.

Use a drop or newspapers to cover the ground to absorb any fluid spills.

Remove Plugs

Next, you need to remove the drain plug and the fill plug. When looking up the transmission case, the drain plug is in the center while the fill plug is directly above it going toward the front of the car.

Use your wrench and 24mm socket to remove the fill plug first. You may hear a hissing sound. This is normal.

Remove the drain plug next with the 10mm hex socket. Place your one or five-gallon bucket underneath the plug first, though. Open it slowly to avoid a gush of fluid going everywhere.

Drain the Fluid

Allow the fluid to drain out of the plug. This can take a few minutes as the stream slows to a trickle. 

Pop the hood while waiting for the transmission fluid to empty. Remove the engine cover, too. This allows your funnel’s extension to reach the fill plug easier.

Change Crush Washers

While waiting for the old fluid to drain, clean both plugs and replace the crush washers

The washers fill in gaps and keep any fluid from leaking out. Over time, however, they can weaken. Replacing them is important to keep your hybrid running smoothly.

Replace Drain Plug

Once the old fluid has been removed, replace the drain plug. Use your torque wrench along with the 10mm hex socket. 

You will need to set your torque wrench to 29 ft-lb to ensure it is on properly.

Add Fluid

Thread your extension hose down through the hood of the car to the open fill plug. Make sure your funnel is securely attached, as well.

Look at the fluid that drained out. We like to use a measuring device to catch the old fluid. This way, you will know how much to put back in.

That being said, most Prius models take about four quarts. If you see the fluid rising to the top of the fill plug, you can stop. As mentioned above, a few drips over the side are okay, too.

Replace Fill Plug

Screw the fill plug back in using your torque wrench and 24mm socket head. Like the drain plug, you need to tighten it to 29 ft-lb.

Alternative Tools

Changing your transmission fluid in your Prius the old-school way is not a difficult process. That being said, there are some alternative tools you can use to make adding fluid easier.

A vacuum transfer pump replaces transmission fluid by placing the nozzle in the fill plug and pumping up the pressure. 

An electric pump essentially does the same thing, though, you have to plug it in instead of pumping up the pressure. You also have to add quarts of fluid one at a time. You can add up to four in the vacuum pump.

The last option is a hand pump. Although this is an inexpensive way to go, we prefer the old-school way of using a funnel. When using a hand pump, you have to hold it steady, continually pump, and add fluid simultaneously.

Conclusion

A Prius transmission fuel change does not have to be done often, nor is it a difficult process. On the other hand, it is important for the overall performance and longevity of your vehicle.

Equally important to your Prius maintenance is ensuring the hybrid battery is in utmost working condition. If you find yourself in need of a hybrid battery replacement, you can find top-notch new and reconditioned batteries here that last longer and perform better!