Supplies Needed

• 10mm Socket
• 21mm Socket
• 24mm Socket
• 6mm Hex Key
• Floor Jack
• Jack Stands
• Level
• Drain Pan
• ~3qt Toyota WS rated transmission fluid
• Oil pump or Funnel with a hose
• OBD2 scanner

When to Change your Toyota ATF

The dealership told me that the transmission fluid should be changed every 30,000 miles, which seemed a little frequent to me, but after seeing how little is actually changed when you do it and how little fluid is actually contained in the transmission, I think that is a good interval.  Please note that your Toyota does NOT have lifetime fluid in it (no cars actually do).

How To Do It

1. Lift the vehicle

My driveway was at an angle such that I only had to lift the front of the vehicle in order to access the transmission pan.  It isn’t as important that the vehicle be level for draining the fluid, but the closer you can get to level the more accurate you will be.  If you are unsure where the lift points are for your vehicle, consult your owners manual.  Always remember to use jack stands to support a vehicle that you are going to work under.

2. Remove The Driver’s Side Wheel

The Lug nuts require a 21mm socket.  Alternatively you could also use the lug wrench included with the car.  I like to use a socket, because I can remove the lugs faster with my impact wrench.  There shouldn’t be a whole lot of torque on these lugs, so it isn’t hard to remove them.  If you opt to not use an impact wrench to remove these, then you will want to at least break them loose before you lift the vehicle from the ground, and then remove them completely once the wheel is in the air.

3. Uncover the Transmission Fill Plug

Once you have the wheel off, you will see the side of the transmission, except for a small plastic cover.  You will need the 10mm socket to remove the two bolts holding this plastic cover that hides the transmission fill plug.  These aren’t very tight.  Using my deep-well, impact socket I was able to just grab on to the socket and twist them out by hand.
Once the two 10mm bolts are removed, you don’t need to remove the third fastener holding the cover in place.  The cover can pivot out of the way revealing the transmission fill plug.

4. Remove the Transmission Fill Plug

The transmission fill plug requires a 24mm socket.  It isn’t on there very tight, so it shouldn’t take much to remove it.  The plug doesn’t have a significant enough shoulder to prevent it from falling inside the socket, but all I had to do was invert the socket with my hand underneath it and the plug fell right out into my hand.

5. Remove Transmission Drain Plug

The transmission drain plug requires a 6mm hex key to remove.  You will likely have some fluid come out when you remove this, so you will want to have your drain pan underneath it while you are removing the plug.  This also wasn’t fastened very tight, so was easy to remove.  You may want to wait until the fluid finishes draining before moving to the next step, but you don’t have to.  It just depends on how much ATF you want on your hands/tools.

6. Remove the Fill Level Tube and Drain Transmission

There is a small plastic tube that regulates the amount of fluid in the bottom of the pan.  This is threaded into the drain hole for the transmission and requires the same 6mm hex key to remove.  You cannot see it until you start to remove it, but if you push your 6mm hex key up into the hole from the drain plug, you will feel it seat into the hole.  You will want to be gentle with this as it is a plastic part.  It doesn’t take much force at all to remove, you could even do it without a wrench.
With the plastic tube insert removed the fluid will drain more or less completely.  You should get about 2 quarts or so of old transmission fluid out of the transmission.  It will likely be fairly black, but at closer inspection, you will see that it has a reddish hue to it.

7. Replace Plastic Fill Tube

Once the fluid has all drained out, you will want to put the fill tube back into the transmission.  I suggest hand threading it in with the 6mm hex key.  You want to be careful not to cross thread it or over torque it.  It doesn’t need to be pushed in hard, just inserted all the way up until the threads bottom out in the hole.  Don’t replace the drain plug yet, but leave the hole open with your catch pan underneath it.

8. Ensure the Vehicle is Level

In order to make sure that you add the correct amount of fluid, you will need to have the car level.  I placed my level against the body of the vehicle in the middle where the two parts of the body are pinched together.  The closer to level you are, the more accurate your ATF volume will be.

9. Fill the transmission

Using your hand pump or funnel with a hose, add ATF to the transmission until it starts to run out of the drain hole again.  As to what sort of transmission fluid to use, you need to make sure that the fluid meets the manufacturer specifications.  In my particular case, this 2014 Toyota Sienna requires Toyota WS fluid.
You can pick up Toyota brand ATF at your nearest dealership parts counter, but it is very expensive that way.  I want to say that it sells for about $40 per quart.  It turns out that there are a lot of different fluids that meet this standard that are cheaper, because they don’t have a Toyota sticker on them. I happened to buy Valvoline Max Life Full Synthetic, because it was at my local AutoZone and a quick check on the bottle shows that it indeed does meet the Toyota WS spec, and it was less than $20 for a whole gallon.

10. Replace the Drain and Fill Plugs

Don’t worry about waiting for the drain plug to stop dripping, because until you have verified the temperature of the ATF in the transmission, it is likely overfilled, at least a little.  The plugs don’t require a lot of torque, just snug them down enough that they don’t leak.  The drain plug will be coming out one more time, but the fill plug can be secured and covered back up.

11. Start the Engine

Without removing the car from the jack stands, go ahead and start the engine. We are doing this to get the fluid that we have just added mixed together with the rest of the fluid in the transmission so that we can get a better temperature reading.  You will note that we are only replacing about 1/3-1/2 of the transmission capacity, and we have to get it to a consistent temperature in order to verify the fill level.

12. Check The ATF Temperature

The most accurate way to check the ATF temperature is to use an OBD2 scanner.  There are lots of different ways to do this using tools like this, but I prefer to use an OBD2 scanner app on my smartphone paired with a Wi-Fi or Bluetooth OBD2 adapter.  The app that I used is OBD Fusion for iOS.  It requires that you also purchase the optional Toyota Pid pack ($9.99) through an in-app purchase in order to get the ATF temperature.  Once you do that you can add a gauge to the dashboard to show the live ATF temperature.  The car must at least be in the ON position to check the ATF temperature, but in order for the fluid to circulate, the engine must be running.

The temperature of the ATF must be between 104 and 113 degrees Fahrenheit.  I like to put my foot firmly on the brake and put the vehicle in drive and manually shift through all the gears during this process to mix the fluid well, but you don’t have to do that.

13. Turn the Engine Off

Once you see that the temperature is within the required spec, wait a few seconds to make sure that the temperature is stable, then turn the engine off.

14.  Drain Any Excess Fluid

Now that the fluid is the correct temperature open the drain plug without removing the filler tube and let any excess fluid drain out.  The vehicle should still be level for this step.  Once the fluid stops flowing at this step, the transmission fluid level is correct.

15. Replace All Plugs, Covers, and Wheels

It is now time to put everything back together.  The plugs for the transmission don’t need to have any significant amount of torque on them.  Just tighten them up enough so that they will not leak.  Replace the cover in the wheel well and secure it with the two 10mm bolts, once again, they don’t need a lot of torque.  When you put the lug nuts on the wheel, you won’t be able to torque them to spec with the wheels in the air, so just hand tighten them so that they are snug enough that the wheel does not feel loose.

16. Lower the Vehicle

You are now ready to lower the vehicle from the jack stands.  Always take care to lower the car slowly.  Cars are heavy and sudden jolts can make them fall off of the jack, and that is how things get damaged or people get hurt.

17. Torque Lug Nuts to Spec

The Lug nuts on the 2014 Toyota Sienna should be torqued to 76ft-lbs.  This should be done in a star pattern, skipping one bolt as you go around the hub.  This ensures that they are tightened down evenly.  I like to go around the hub two times with the torque wrench just to make sure that they are all correct.