Changing ATF in Toyota with No Dipstick ?

[willbur]

Is all this really necessary? Assuming a temp delta of 120 degrees and a Toyota trans fluid change volume of 3.2 quarts yields about 4.8 oz. difference between room temp and hot trans fluid volume. Unless you are so precise that you're changing fluid using an eye dropper, this is way overthinking. Are new generation transmission this sensitive to fluid volume (I'm assuming published Dexron thermal properties as being representative and 3.2 quarts change volume as stated from a previous post)? I really would like to know.
I believe a more typical change volume is probably more like 10 quarts. In this case, the volume difference would be about 15 oz- less than 1/2 a quart. Would this make any difference in trans performance?

 

[Oro_O]

Originally Posted By: willbur
Is all this really necessary? Assuming a temp delta of 120 degrees and a Toyota trans fluid change volume of 3.2 quarts yields about 4.8 oz. difference between room temp and hot trans fluid volume.


Nope, you are right - it is not. I refill and then idle for several minutes to get the temp up into range, then check the fill. Which achieves exactly the desired result with none of the nonsense.

 

[nthach]

Originally Posted By: Fsharp
Originally Posted By: leje0306
When I owned my 2012 4Runner, I recall there was a procedure that included jumping terminals on the obdii port that would cause the trans temp light to flash at the correct temp.. I’m not sure if that applies to your Lexus’


Same deal on my 2007 ES350. Jumping 2 pins in the port and a certain procedure of starting the car and moving the shifter. In mine not the trans temp light, but the transmission gear indicator display would flash.
It worked, but next time I’m letting the dealer handle it.

I did that with my parent's LS430 as well. It does work, but I had to level the car on 4 jackstands and even so I was scared of the car falling on me. I used my phone's gyroscope and a bubble level carefully laid on the roof lengthwise. I ran the car per TSRM to enter fluid check mode and I let the fluid run out to a slow drip.

I topped off the tranny with 2oz of ATF WS and considered it done for 30K. I'll bug The Critic next time.

 

[JTK]

It really is insane if you watch some online videos for the "book" procedure with all the Toyota equipment. Designing it so you have to pull a vacuum on a the transmission case of a running vehicle if the fluid temp is above ~103F (or what ever it is)??

I get it that a shop won't have the luxury of being able to drain ATF cold and refill cold like we would at home, so they need all this extra stuff, but this is some seriously ridiculous engineering .

If I owned a Toyota product and planned to do a drain/fill. I'd do it cold and add back what ever came out. Maybe later on down the road, I'd try to be as level as possible, start the vehicle cold and let it run up close to the that minimum temp by shooting the trans pan with a temperature gun and then pull the fill/level check to verify.

 

[sambojoho]

I use a large plastic measuring cup to get an accurate measure of what was drained. Drain it cold. works perfectly, don't need to check level.

 

[Gebo]

That's what I do now but I made a mistake when I first changed the ATF in my ls430 and is350. Just trying to make sure they are at correct level now.

 

[Aichiguy]

I read somewhere that the volume difference this transmission's fluid hot vs. cold is about half a quart. I'm in the camp that drains fluid at ambient temperature and replace same amount.

 

[The Critic]

Originally Posted By: doitmyself

THE Critic, is your shop that careful about these details?

While I am aware of the situation described above, I have never bothered to compensate for it. Here's why:

Despite the difference, the transmission pan still stays fairly level when checked using a level.

I also fill and check the trans at the lower end of the specified temperature range, which means I am adding more fluid anyway. To me it is a non-issue.