How to Drain/Refill Automatic Transmission

I see a lot of people finding they are short ~500mL the first time they do this. I did a full flush (~12L) at 100,000km (60,000mi). I had to add 550mL more than what I took out.

Today, I did a drain and fill. I now have 135,000km (~84,000mi). 2.65L came out when I drained it. I added 2.8L, knowing that I had filled it to the correct level on the previous service, figuring the extra 150ml would drain out the overflow. When my AT Temp light came on, I pulled the overflow plug and nothing came out. I added an extra 200mL, let the truck cool for awhile, and repeated the process. This time 125mL drained out of the overflow. This means I added 225mL more than I drained.

This seems to suggest the 225mL of fluid went missing since the last time I did a full flush. I'm not spilling fluid so unless my measurements are wrong, I'm not sure where the fluid is going. From what I've read, transmission fluid shouldn't get low unless there is a leak. I've never found any fluid under my truck. Either there is something wrong with the drain and fill procedure, the transmission is using fluid, or it's an unnoticeable leak?

 

I don’t know if this is the culprit or your procedure, but when I’m sitting in the truck waiting for it to get to the proper temp so I can pull the check plug. I’m sitting there with one foot on the brake and cycling through the gears. Hoping this will circulate the fluid faster and heat it up consistently throughout the tranny. Who knows, maybe it’s also getting trapped air out of the converter.

 

Based on the overall capacity, that's a difference of only 2.3%. I think you'd have to do the same procedure and measurements several times to get a good sample and averages. Even then, if it remains such a small percentage difference, I don't think it is something to worry about.

 

I think your right for the majority. I live in the N.E. with cold winters. My tranny would slip before total warm up when cold. When I checked, it was almost a quart low. After I did a pan drain and fill, the next winter , no problem. I never had a problem in the summer or after warm up in the winter.

The problem with slipping seems to be with fluid expansion. Warm vs cold. I contributed this to low from factory, and based on other post, I do have a tow package thus an auxiliary cooler that was under filled. This has been pointed out numerous times. I don’t think its right to say a quart low is ok.

edit.
I apologize since you didn’t quote a qt.

 

Yeah, a quart low is ~10% difference, certainly significant enough to be concerned. I was just pointing out that a ~2-3% difference when following the proper procedure is probably not very significant. It would be interesting to know the difference between checking at the low end of the temp range compared to the high end. Some smart person could probably do the math on thermal expansion.

 

Yeah, it's probably nothing to be concerned about. My truck is still driving and shifting like it always has, and I've never had any issues.

 

The 5mm hex on my overflow bolt is stripped out...any tips for removing? Can I replace it with something off the shelf?

 

Drill it and use an EZ out/screw extractor. A dealer might have one in stock. I think it's the same thread as the drain bolt. Otherwise a bolt supply store.

 

Did a check of my transmission fluid level today. I have a 2015 tacoma prerunner v6. Got the AT temp light to come on for 2 seconds by following the procedure in this forum. When the light came on again steady I removed the jumper from 4 to 13 and plugged in my scan guage. It read 100f, that is when I removed the 5mm plug and got a tricky of fluid. I let it run in park until the light on the dash started to flash indicating temp of fluid was too hot to check the level, at that point the scan guage read 114f. So it looks like the proper temp range for my truck is between 100 to 113f to check your fluid level. In the future I will follow the jumper procedure to get it to enter the check mode and then plug in my scan guage to get the temp reading. Sincerely Tim

 

I once had a VW TDI with an automatic and it had a similar procedure for checking the trans for the correct amount of fluid in it. It also had no dipstick for the auto-trans. It was said that if you let the fluid drain out of the leveling tube until it quit draining, it would be too low. The way to ensure you had the correct quantity in the trans was to make sure you had a steady stream coming out the tube and after the first burp or two or three, as they called it, put the plug in. The burp they were referring to was when the fluid coming out of the tube appeared to be interrupted as it came out. When the vehicle is running during the check the fluid in the trans is in continuous movement.
This is how I set mine, I try and put the plug in as soon as I can after the first burp or interruption. I don't let it stop coming out before I put the plug in.

 

I just Scangage the fluid in the trans pan temp to be over 100 and less than 115. Pull the check plug and ensure a slow trickle. Reinstall the plug and done. No longer bother with the pin jumping procedure, not worth the effort.

BTW, on my 2010, I have used Mobil 1 ATF since the first fluid change, and forget an exact miles but likely each 30,000, I do a complete flush and fill by removing the fluid return line, and shift through all gear selections while running and pumping fluid into the catch bottle. When the fluid comes out bright red same color as new, the hose is reconnected and the pan is slightly overfilled. Then I use the Scangage, watching for 100*f temp to set the final fluid level.

Super easy with two people doing it. That method I mentioned, flushes and purges the entire system. While my truck no longer uses the oem setup of fluid in the radiator or aux cooler, Scangage temp of fluid in the pan on a hot summer day never exceeds 165*f.

 

Checked the temperature range with my scan guage verses the AT temp light on the dash . Light comes on at 98f and starts to blink at 114f. So the proper temp to check fluid level is between 98f and 113F. I have a 2015 pre runner with V6 automatic. Sincerely Tim

 

Correct, the specified temp was changed in 08 for all models (see the attached TSB). The OP wasn't updated to reflect this.

 

Fantastic write up!!

 

Did this service today!

Thank you for the write up!

 

thank you for your service

 

LOL

 

To answer the unanswered question on this thread about 08 Tacoma Prerunner having the ATF light. It does. It does not light up during normal key on. If you shine a flashlight to the cluster in the area you will see the outline of it. It will light if you follow this procedure. Never knew it was there for 20 yrs.
I am going to do this service. I practiced the jumper method and got the atf light to work. I bought a OBD2 connector from Ballenger to make jumping easier. My
Jumper is in empty connector with jumper to pin 4 and 13. The last thing you need to do is damage your Obd2 port with repeated paper clip jammings. Plus it’s easier than bending over and counting the ports with your head upside down. For those of you doing this on the regular it might be helpful. The connector was super cheap. $15 including shipping.
http://www.bmotorsports.com/shop/product_info.php/cPath/109_151/products_id/508

 

Thats the method I use with the dongle, thanks to TW I made one 2 or 3 yrs ago and it makes life easier.

 

I’m due for this procedure and wanted to ask if I could just use my Scan Gauge Tool for the Transmission Temp?

Also do you recommend just ge Drain & Fill or the Full Flush?

Im the 2nd owner and this is my CarFax (current mileage 168,520) Thanks in advance!