How To Drain & Fill Transmission Fluid For The 5th Gen 4Runner and How It Differs From A Flush – A Step-By-Step Guide
If you’re like me and enjoy doing your own maintenance, dealing with the transmission seems daunting. It’s a large and expensive component that you want to take care of in order for it to last a really long time. I really didn’t want to mess anything up or damage anything, so I considered just having Toyota take care of the transmission fluid for me. After contemplating for around 10,000 miles, I finally decided to just do it myself.
I wanted to learn for both the experience and so it’s easier/cheaper for me to do down the road. The cost alone for the supplies was around $174 (6qts). Taking it to a dealership, I’d imagine, would be a pretty penny. I just needed to make sure I could find all the required supplies for the task, along with some kind of guide.
This being my first time servicing any transmission, I searched online for quite some time only to find vague results for the 5th Gen 4Runner. Eventually, I managed to gather all of the part numbers and I’m happy to present you with a full guide on how to replace the transmission fluid for the 5th Gen 4Runner.
Disclaimer: I must warn you that I am no master vehicle tech, nor do I tear transmissions apart. I am also not a scientist. There will be a lot of compiled information and my personal opinions based on my research and my personal experiences as an aircraft mechanic. It is completely okay to have your own opinion; my goal is to help out the 5th Gen community with a guide for DIYers.
Please take what you want from this article and use it for what you need!
The Overall Service & Fluids Used
The task might seem a bit overwhelming, but in reality, it’s not bad. You don’t need any special tools, although a way to read your transmission temperature is super helpful. Set aside a good amount of time for this service, especially if it’s your first time doing it. I planned for about 6-hrs just in case I needed any extra parts or tool runs. Once you start this process, you cant drive the vehicle at least until you get fluid back inside.
As far as transmission fluid, I went with genuine Toyota ATF WS, mainly because it’s what the manual says to put in. If I didn’t use official Toyota fluid with the exact additives required, then I might be kicking myself later. I was able to acquire it at my local Toyota dealership for $9.45/quart, which isn’t bad. I highly recommend just using the required fluid.
From the 2019 owner’s manual: “Using transmission fluid other than “Toyota Genuine ATF WS” may cause deterioration in shift quality, locking up of the transmission accompanied by vibration and, ultimately, damage to the vehicle’s transmission.”
How To Read Transmission Temp
Go ahead and start coming up with a way to read your transmission temperature. This part brought my maintenance tempo to a halt by not being as fully prepared as I thought I was. I found out that there are a couple of ways to get this read out.
The 4Runner’s Maintenance Mode or Trans. Temp Check Mode
This way will always be possible, as long as you can obtain a 16-20 gauge wire for your OBDII port. In this method, you will jump two different terminals and put the vehicle in maintenance mode. After doing so, you will follow some specific steps in order to get your vehicle ready for the transmission temperature check. I’ll explain this one later.
Have An ODBII Device For Read Out
This one comes in many shapes and forms: ScanGauge, various phone apps, UltraGauge, and even readout tools designed for maintenance.
I was able to use my UltraGauge MX. The only issue with having the UltraGauge is it needs to be programmed in order to read out manufacturer-specific information.
You need specific manufacturer codes in order to access such information. It can be a complex code entry on your device in order to get this. After some deep internet searching, I was able to find the codes for the UltraGauge MX.
Programming and codes are something I know very, very little about, so I won’t get into it here. Above are the exact codes I used in order to get the transmission pan temperature programmed on the UltraGauge MX.
Laser Temperature Gauge
I would use this as a last resort due to possible inaccuracies. You would also need a laser thermometer, which is not something I just have laying around. I read this was possible with the laser pointed at the more forward section of the pan where the filter/strainer suction happens. Hey, you got to do, what you got to do sometimes.
Why Knowing The Transmission Temp Is Important
In the picture above, “1” would be the overfill plug, and “a” would be the fluid level. As fluid temps increase, they tend to expand and become more viscous depending on their specific properties. As the temps decrease, the opposite happens, they contract and become less viscous.
This is crucial because the fluid check valve/overfill plug on your transmission pan is designed to be read at a specific temperature range. If you pull out the fluid check plug on your cold transmission, nothing should come out, because the fluid is contracted and rests below the overfill on the inside of the plug.
If you pull the check plug on a hot transmission that has been running, some fluid might come out due to the thermal expansion of the fluid. The fluid level would sit higher in the pan, so fluid would be allowed to come out of the overfill. So, in order to make sure the proper amount of fluid is in the transmission, it needs to be at a specific range of 104F – 113F.
You will be able to see this better later when pulling the pan off and getting to look at the overfill plug.
Drain & Fill Vs. Full Fluid Flush
This is a debatable topic and I would say to do some research to form your own opinion. It is your vehicle, and how you take care of it is up to you.
I chose to go with a drain and fill, strictly based on my fluid color upon initially draining the pan. If my fluid appeared very old and degraded, then I more than likely would have just flushed the entire system.
Your transmission has many moving components, some of the components will break down faster than others on a relatively small scale. The older fluid doesn’t have as good lubrication properties or heat dissipation compared to the new fluid. Therefore, it causes a more rapid breakdown of components.
Depending on the life of the fluid and the shape it is in, some of the suspended material from components breaking down can actually help specific components such as the clutches, especially if they are worn. Overall, some of that suspended material from component breakdown might be what is helping your clutches shift from gear to gear with the added friction.
Your valve body has tons of passages within it, and over time, material and sludge start to build up. With newer ATF fluid having excellent cleaning properties, flushing the whole system can possibly clog passages by moving sludge or material through them. Personally, I feel like this could only happen if you never performed the appropriate maintenance on time.
So, If you are at a normal interval (like mine), or on time for maintenance, everything should be fine. For transmission fluid that looks close to new, you can’t go wrong with either a drain and fill or a full flush. A flush would more than likely be overkill.
If your 4Runner has high mileage or you don’t know the previous maintenance history, then checking fluid quality and doing a drain and fill is probably safer in my opinion.
Why I Chose To Drain & Fill
The 4Runner Maintenance Guide mentions replacing the transmission fluid for the first time at 60,000 miles. I wanted to check the condition of the fluid first, then make my judgment.
Based on my above findings, I chose to do a drain and fill because I wanted to leave some of the older fluid in the transmission with some of the suspended material. Also, my transmission fluid wasn’t really that bad, and I didn’t want to overdo it. By pulling the pan, and filter, and letting everything drain for a bit, I was able to drain approximately 5 quarts of transmission fluid. For reference, the total volume is about 11.3 quarts.
Removing nearly half of the fluid will introduce enough new fluid to the system keeping components properly lubricated but also leaving some material in the fluid. That basically means it should help keep components clean on a more gentle scale, rather than force new fluid through all at once.
Considering how the fluid appeared at a 60k interval, I plan to do drain and fills in 30k intervals going forward. The Maintenance guide calls for the next check at 120k miles, so cutting that interval in half at 30k miles will give me peace of mind. It also gives me more time to decide between a drain and fill or flush.
Here are a couple of informative videos and articles on transmissions that I thought were helpful
- The Car Care Nut – Specific to an early 5th gen (Toyota Master Diagnostic Tech)
- Chris Fix – General scope of transmissions (5 min mark talks about internal components)
- Toyota A750 Transmission – Back story and design of the 5th Gen transmission
Tools & Supplies
The hardest part about performing this maintenance is the temperature check. The parts, tools, and supplies required are relatively minimal.
As far as the transmission filter goes, you don’t need to replace it, unless it’s in rough shape or full of metal. I chose to replace it since I was dropping the pan, and I had previously purchased it just in case.
Prices may vary by location, but I will give my prices here in Hawaii just for reference:
- Check/Overflow Plug & Drain Plug Gasket
- PN: 90301-15004
- Quantity: 2
- Price: $3.10/ea
- Fill Plug O-Ring
- PN: 90430-18008
- Quantity: 1
- Price: $2.84
- Oil Pan Gasket
- PN: 35168-60010
- Quantity: 1
- Price: $28.19
- Transmission Filter
- PN: 35330-60050
- Quantity: 1
- Price: $69.34
- Transmission Filter O-Ring
- PN: 90301-31014
- Quantity: 1
- Price: $3.99
- Toyota Genuine ATF WS
- PN: 00289-ATFWS
- Quantity: 6qts for drain and fill, 12qts for flush
- Price: $9.45 a quart X6 = $56.70
- Drain Container To Catch Fluid
- Container To Measure
- Shop Towels
- 10mm, 12mm, and 14mm Sockets
- Shallow Wall 24mm Socket
- 5mm Allen
- Fluid Transfer Pump
- 16-20 Gauge Wire
- Torque Wrenches For:
Step 1. Find Level Location & Allow The Transmission To Cool
This is one of the most important steps. In order to get an accurate reading, the vehicle is going to need to be level or have all four corners off the ground.
Letting the transmission cool is important for the temperature check. The transmission heats up relatively quickly, and your 104F to 113F window is pretty small. Having all the extra time for you to do the check and install the check plug is nice to have.
Step 2. Remove Refill Plug
The 24mm refill plug is going to be located on the passenger side towards the upper rear end of the transmission. Removing the refill plug should happen first as good practice. If you first remove the drain and later find out you cannot remove the refill, you’ll be stuck (literally and figuratively).
Step 3. Remove Drain Plug & Catch Fluid
Catching all the fluid is important to know how much to refill later. The 14mm drain plug is going to be the furthest aft and looks like a normal drain plug. The other one with the 5mm Allen key socket in the center is the fluid check plug. It also has the word “check” on the end of the plug.
Step 4. Fully Drain, Then Start Removing Pan Bolts
Once your fluid has been drained, soft-install the drain bolt and begin removing the pan.
Step 5. Attempt To Catch The Remaining Fluid
The transmission pan will more than likely have a good bit of fluid still in it. Fluid will also still be draining from the valve body and transmission filter. Lower the pan slowly and set it below to catch the remaining fluid for a bit.
Step 6. Remove The Filter
If you are replacing the filter, there will be a good bit of fluid that comes out upon removal. For that reason, keep the drain pan or catch can close by. Remove the filter via the four 10mm bolts holding the filter assembly in place.
Gently move it back and forth until it is unseated. Make sure to remove the O-ring as well, mine decided to stay behind.
Step 7. Combine All Drained Fluids
I used the pan itself as a catch device and an old jug to get my total amounts. I used the jug to pour the fluid into old quart-size jugs for my measurement. In total, I was able to drain 5 quarts.
Compare and inspect your fluid to new fluid to decide whether you want to do a drain and fill or a full flush. Either way, you will be re-installing the pan and filling the same amount of fluid that you drained.
Step 8. Check Valve Body Bolt Torque
This is an added but not necessary step. The older the vehicle, the more I would recommend doing it. There are 19 – 10mm bolts on the bottom that hold the lower valve body on. Over time, vibrations can cause the bolts to loosen, especially if you take your 4Runner offroad.
Your valve body has a couple of layers to it. In between are gaskets that make sure fluid is going in the right places. If the bolts were actually loose, this could allow fluid transfer into chambers within the valve body where it’s not supposed to.
I checked mine at their factory torque spec of 8 ft-lbs and only one budged slightly. When checking, torque in a criss-cross or star pattern.
If you don’t have a torque wrench capable of 8 ft-lbs, just make sure none of the bolts are really loose. If you accidentally over torque, you could damage the gaskets and run the risk of other potential issues.
Step 9. Install Transmission Filter
Before installing the filter, make sure to have your new O-ring ready (PN: 90301-31014). Also, compare the old parts to the new parts.
Install the O-ring and lube it up with some ATF for smooth installation. The four – 10mm bolts get torqued to 7 ft-lbs.
Step 10. Prep Transmission Pan
Notice there are four small magnets located at the bottom of the transmission pan. Remove, inspect, and clean them. A thin layer of fuzz would be normal as the metal components inside will break down over time. This is the stuff that is heavy enough to make its way to the bottom and get caught by the magnets.
The left is a cleaned magnet, and the right is uncleaned.
For cleaning out the pan, I opted to not use any harsh cleaners or any other fluids. I wanted to minimize the chance of contamination, so I just used some ATF and a clean cloth. After cleaning the pan thoroughly, reinstall the magnets. Remove the old gasket and clean up the matting surface on the pan and at the transmission.
With the pan prepped and ready, it should look like the image above. Now you can also get a better look at the overfill plug.
Step 11. Install Transmission Pan
Carefully guide your pan up to the transmission with the gasket (PN: 35168-60010) in between. You want to make sure the gasket sits properly between the pan and your transmission. Once it’s in place, go ahead and soft-install some bolts on all sides to make sure the gasket is lined up. If the gasket is lined up all the way around, go ahead and tighten the bolts by hand.
Now it’s time to torque the bolts to spec. In a criss-cross/star pattern, torque the 20 – 10mm bolts to 62 in-lbs. Doing this will ensure the gasket is evenly sandwiched between the two surfaces and prevent leaking or damaging the gasket.
Complete that pattern twice to ensure that the proper torque is applied all the way around.
Step 12. Install Drain Plug
Install the 14mm drain plug with the gasket (PN: 35178-30010) and torque it to 21 ft-lbs.
Step 13. Fill Transmission With Measured Fluid
Again, I drained about 5 quarts of fluid. This may vary if you don’t pull the pan, or don’t pull the filter.
I added 5.5 quarts to be on the safe side, due to some small spills during the pan drop. I would rather slightly over service than under service in this circumstance. Use your best judgment.
If you don’t add enough, you’ll have to restart your temp check process. If you overfill, the extra will just come out of the overfill plug. During the final temp check, you want some fluid to come out a little then re-install the overfill plug.
Step 14. Soft Install Your Refill Plug And Prep For Temp Check
At this time, prep your refill plug (PN: 90301-15004) and soft-install it. With the transmission fluid refilled, make sure you have all the required tools and parts standing by for the final temp check.
This process moves pretty quickly, so the less time you spend scrambling for parts and tools, the better. The tools needed will be:
- Catch Container
- Ratchet w/ 5mm Allen
- P/N: 35178-30010
- A Way To Read Transmission Temperature
Double-check all of your work and make sure everything is put back together properly before turning the engine over.
Step 15. Transmission Temperature Check
If you have a tool that can read out your temperature, and you have a valid temp of 104F to 113F, then you can move to the fluid check procedure.
If you are using the vehicle’s maintenance mode/ temperature check mode, then follow the steps below.
For troubleshooting, check out this video (7:40 mark). An indicating light of “D” or “A/T OIL TEMP” is dependent on you having 4WD or 2WD. In Step 6 of this procedure, if you have 2WD, your indication should be “A/T OIL TEMP”.
Vehicle Maintenance Mode
- With the vehicle off, install a jumper cable from pins 4 and 13 on your ODBII port. Double check you are using the correct terminals!
- Start your vehicle and make sure all electrical systems are off.
- If you connected the correct terminals, a lot of the dash lights will be flashing on and off. This means you are in maintenance mode.
- With your foot on the brake, cycle from Park to Neutral a couple of times. Once complete, put the transmission back into Park.
- From Park and with a foot on the brake, go to Neutral. Cycle back and forth from Neutral and Drive quickly until your “D” indicator on the dash becomes solid. When you see this, put the shifter back into Park and remove the jumper cable previously installed.
- Now, the vehicle is in fluid check mode, allow it to idle until you reach the desired temp. When the fluid temperature is below 104F, the “D” light will be off. When the temp is at 104F, the “D” light will come on solid. If the temp exceeds 113F, the “D” will blink, letting you know it’s too hot to check the fluid level.
Step 16. Fluid Level Check
With your temp at the precise range of 104-113F, it’s time to pull the check plug. Have the gasket ready to go, along with a catch container.
- If you have fluid come out, this means your fluid level is above the desired amount. Allow the excess to drain out of the overfill/ check plug. Once the fluid goes from a stream to a dribble, re-install the plug with the gasket (PN: 35178-30010). Now your transmission fluid level is at its proper level.
- If you don’t have fluid come out or if you only have a couple of drops or so, then you would need to turn the vehicle off and restart from adding fluid (Step 13).
Step 17. Test Drive & Leak Check
If nothing leaks, torque the check plug to 15 ft-lbs and you’re done! Congratulations, you have now successfully serviced your transmission. After you drive a bit, it wouldn’t hurt to do another fluid level check to double-check your work.
Full Flush Notes
A full flush is done by completing multiple drains and fills (without dropping the pan) until the equivalent amount of the full 11.3 or so quarts have been changed out of the transmission.
You could also use the transmission cooler outlet/ return line and attach a hose to it. Then, turn the vehicle on and allow the internal pump to push out the fluid. Preferably, use a soft line or hose in the forward area of the vehicle closer to the transmission cooler. You could follow the top line in the picture above.
If you go this route, you’ll want to monitor closely and not allow the pump to cavitate. You would pump out about 2-3 quarts of fluid, turn the vehicle off, and add slightly more fluid through the refill port. Do this until you reach 12 quarts or the fluid color is new.
The overall process of changing your transmission fluid isn’t too bad, just make sure you have all the parts, tools, and supplies ready. Also, don’t forget to allow yourself enough time to complete the job.
After completing this, I haven’t really felt anything different, nor should I. Else, I was probably overdue or something else was wrong. If you went a long time without doing it, you probably would notice a difference. Knowing that I introduced a decent amount of healthy ATF to the system gives me peace of mind. Hopefully, staying on top of future maintenance intervals will lead my 4Runner to a long-lasting life with no major component failures.
Like I said before, whether you drain and fill or flush the whole system is up for debate. If you are thinking about servicing your transmission, you’re already on the right path. Doing something is going to be better than doing nothing at all. Your transmission is an expensive component that should and will last a very long time if you take care of it.
I recently did the same. Also, replaced 2 transmission solenoids and added an extra trans cooler.
You should mention the vehicle must remain running when you check the overfill plug at temp. If you shut off the engine more will come out than it should and you will have to start all over.