Are we over exaggerating the perfect ATF fluid level? thermal expansion seems to think we are

[SC Maintenance]

On my Nissan's one side of the stick is cold, and one side is hot, and I can tell you that if you get it full on cold - it is way, way over hot. However the stick is calibrated to Matic J - which was superseded by matic S. I wonder if the properties are that much different? S is a thinner fluid?

 

[The Critic]

On my Nissan's one side of the stick is cold, and one side is hot, and I can tell you that if you get it full on cold - it is way, way over hot. View attachment 214176

Yep- I only use cold if the car has been sitting overnight, and even then, I fill it to the bare minimum.

 

[Astro14]

@apollo18 - the math is still way off, and specious.

Even if your “2oz” calculation is correct (and I don’t think it is), that doesn't mean there is almost no difference across a temperature range. The dipstick “tool” on the Mercedes 722.6 has two ranges - 20C (cold) and 80C (hot).

The range for each is about 1cm. But the two markings on the tool are about 3cm apart. The fluid, over 60C, expands enough to raise the level by over an inch.

So, it’s not a matter of a couple of oz if you get the temperature wrong, it’s more like half a liter to a liter. “Close enough” is good in horseshoes and hand grenades, but not here.

Follow the factory procedure for your car, stop overthinking this, because you’ve now made three separate threads with the overthinking, including using the wrong fluid, when to change the filter as part of a fluid change, and now this.

But your car is no better off for all wandering through the wilderness.

 

[SC Maintenance]

Problem is the Toyota procedure on this is haphazard at best. To the point where a Toyota technician on this board told me that they just measure what comes out at the dealer, and Toyota themselves have issued a TSB and a bunch of new tools themselves.

Given the number of people that have done this task without issue, I do assume the the tolerance is a bit wide.

Toyota sort of pooched this one IMHO. I presume they really don't want anyone changing the fluid anyway.

Anyone know the thermal expansion coeficient for ATF? I have read everything from 0.0001% per degree C, to 0.07%?

 

[Astro14]

Problem is the Toyota procedure on this is haphazard at best. To the point where a Toyota technician on this board told me that they just measure what comes out at the dealer, and Toyota themselves have issued a TSB and a bunch of new tools themselves.

Given the number of people that have done this task without issue, I do assume the the tolerance is a bit wide.

Toyota sort of pooched this one IMHO. I presume they really don't want anyone changing the fluid anyway.

I plug in Techstream, read out the temperature, open the plug per directions, a bit drains out. DONE.

Couldn’t be any easier.

It’s the easiest of any of the autos I have ever owned. No dipstick, crystal clear temperature range, simple procedure.

 

[The Critic]

Problem is the Toyota procedure on this is haphazard at best. To the point where a Toyota technician on this board told me that they just measure what comes out at the dealer, and Toyota themselves have issued a TSB and a bunch of new tools themselves.

The procedure is not haphazard.

The reason why they issued the TSB is because technicians are in a hurry and refused to wait until the trans cooled to the proper temp range. So they developed a tool that allowed for the fluid to be checked when it was hot.

A lot of techs service these transmissions when the transmission is too warm to be checked using the correct method, so they improvise by measuring the quantity drained and refilling with similar. If you think about it, this is a very bad idea if the last person had done the same.

 

[SC Maintenance]

The procedure is not haphazard.

The reason why they issued the TSB is because technicians are in a hurry and refused to wait until the trans cooled to the proper temp range. So they developed a tool that allowed for the fluid to be checked when it was hot.

A lot of techs service these transmissions when the transmission is too warm to be checked using the correct method, so they improvise by measuring the quantity drained and refilling with similar. If you think about it, this is a very bad idea if the last person had done the same.

Looks pretty haphazard to me.

First - get the car level. OK, this intuitively makes sense but still pretty tough. Especially since the car needs to be idling which means you need to do it outdoors in most cases. Is you driveway perfectly level?

Second, get the trans to temperature. However even if you watch car care nut he starts at the bottom of the temp range, and when he is done its already over temp. The range is very small.

Also you have to judge when the fluid goes from a stream to a drip? Someone here did say it goes stream to drip to stop pretty quick, so OK, but its still a judgment. From Toyota "until the automatic transaxle fluid flow slows and only drips come out" What exactly does this mean?

I am not saying the procedure is difficult, but I bet if you did it and I did it, and someone measured - our results would be different. Thats haphazard. If you follow a factory procedure you should get the same result every time, but I bet you wouldn't.

 

[Astro14]

Looks pretty haphazard to me.

First - get the car level. OK, this intuitively makes sense but still pretty tough. Especially since the car needs to be idling which means you need to do it outdoors in most cases. Is you driveway perfectly level?

Second, get the trans to temperature. However even if you watch car care nut he starts at the bottom of the temp range, and when he is done its already over temp. The range is very small.

Also you have to judge when the fluid goes from a stream to a drip? Someone here did say it goes stream to drip to stop pretty quick, so OK, but its still a judgment. From Toyota "until the automatic transaxle fluid flow slows and only drips come out" What exactly does this mean?

I am not saying the procedure is difficult, but I bet if you did it and I did it, and someone measured - our results would be different. Thats haphazard. If you follow a factory procedure you should get the same result every time, but I bet you wouldn't.

My shop floor is perfectly level. That's true for most shops. The requirement to be level is true for every dipstick, every transmission measurement. It's true for oil level as well. Why make a big deal of this?

By the time I park the truck, drain the fluid, change the filter, and reinstall the pan, it's cool. No worries there.

The drip stops quickly. It's not hard to tell.

The procedure, and I've done it a couple times, is among the easiest things I've had to do on a car. Idle engine, shift gears, read temperature, open a plug.

It's so simple, so basic, it's like draining the oil. I just don't see why everyone is making a big deal over this. It's so simple, so easy, that a child could do it.

The problem comes when people try to cut corners, do it on a lift, don't wait for the cool down, etc. But the procedure itself? Simple. Easy.

 

[The Critic]

Looks pretty haphazard to me.

First - get the car level. OK, this intuitively makes sense but still pretty tough. Especially since the car needs to be idling which means you need to do it outdoors in most cases. Is you driveway perfectly level?

Second, get the trans to temperature. However even if you watch car care nut he starts at the bottom of the temp range, and when he is done its already over temp. The range is very small.

Also you have to judge when the fluid goes from a stream to a drip? Someone here did say it goes stream to drip to stop pretty quick, so OK, but its still a judgment. From Toyota "until the automatic transaxle fluid flow slows and only drips come out" What exactly does this mean?

I am not saying the procedure is difficult, but I bet if you did it and I did it, and someone measured - our results would be different. Thats haphazard. If you follow a factory procedure you should get the same result every time, but I bet you wouldn't.

1) Garage with an open door is sufficient - that is how most shops are setup.

2) If you read what I said in post #22, I already addressed this issue. You need to let out the excess in stages and start with a trans that is well below the temp range. If you overfill too much and start letting fluid out at 104F, then yes, you will have an issue.

3) Think of a toilet tank overflow tube. Once the fluid is level, it will slow to a drip. That is sufficient.

This procedure really isn't difficult - it is just different than what you are accustomed to. And no, I firmly believe that you and I would reach the same result every time if you just took a bit of time to execute the procedure with care.

 

[Braapdaddy]

This could all be solved once and all for each vehicle manufacturer by simply having a drain plug and a fill plug as well as the fluid amount printed directly into the case ..........

But of course some will say I live in death valley and the ambients are around 105+and the next guy says I live in the Klondike and it's -20 and the debate will go on in perpetually

With my Toyotas once a good level was determined and operation was as expected I would get a clean tub drain fluid compare with measuring marks and also measure once again by individual quart ....... And put that amount back in each time I changed fluid so far the 2019 Tacoma is up to nearly 190k and 5 fluid drain and fills

 

[hrv]

This could all be solved once and all for each vehicle manufacturer by simply having a drain plug and a fill plug as well as the fluid amount printed directly into the case ..........

But of course some will say I live in death valley and the ambients are around 105+and the next guy says I live in the Klondike and it's -20 and the debate will go on in perpetually

With my Toyotas once a good level was determined and operation was as expected I would get a clean tub drain fluid compare with measuring marks and also measure once again by individual quart ....... And put that amount back in each time I changed fluid so far the 2019 Tacoma is up to nearly 190k and 5 fluid drain and fills

Thats what I have on my 21 Honda HRV....drain and check plug...fill it till it trickles out of the check bolt...easy peasy...

 

[apollo18]

@apollo18 - the math is still way off, and specious.

Even if your “2oz” calculation is correct (and I don’t think it is), that doesn't mean there is almost no difference across a temperature range. The dipstick “tool” on the Mercedes 722.6 has two ranges - 20C (cold) and 80C (hot).

The range for each is about 1cm. But the two markings on the tool are about 3cm apart. The fluid, over 60C, expands enough to raise the level by over an inch.

So, it’s not a matter of a couple of oz if you get the temperature wrong, it’s more like half a liter to a liter. “Close enough” is good in horseshoes and hand grenades, but not here.

Follow the factory procedure for your car, stop overthinking this, because you’ve now made three separate threads with the overthinking, including using the wrong fluid, when to change the filter as part of a fluid change, and now this.

But your car is no better off for all wandering through the wilderness.

Thanks for the reply but I don’t mean to argue or to make it seem as if I am not budging on my argument. I just think there is a misunderstanding.

I stated in post #21 and also My main post that the 2oz argument is only if you did the temp check around 10 Fahrenheit below of above the correct temp check.

I also stated in post #21 that someone doing the temp check at not even close range to there tranny manual will could have upwards of 500mL +++ of fluid variance which is ALOT and I am not telling people to do set there fluid levels at 200f when manual says 100f

I am just saying how if you followed a manual and it says to do it at 100f and you did it at 105f or 95f you are def fine as the volume won’t expand that much in 5f of variance to cause a considerable difference in fluid level

In post 21 I stated how the the fluid variance due to expansion at 80c and 20c could lead to a volume variance up 500mL ++

I never stated or never intended to mean that a 200f tranny fluid fluid would be the same volume as 80f. I stated that anyone who tries there best to get the tranny level as close to the manual temperature can sleep at night even if it wasn’t perfect to the T

Once again I mean no disrespect to you or anyone on this thread. I just feel as if someone doesn’t read my post in entirety could come to the wrong conclusion and I don’t want to be spreading misinformation when I stated all the facts.

I respectfully mean no harm with this reply

 

[Astro14]

Thanks for the reply but I don’t mean to argue or to make it seem as if I am not budging on my argument. I just think there is a misunderstanding.

I stated in post #21 and also My main post that the 2oz argument is only if you did the temp check around 10 Fahrenheit below of above the correct temp check.

I also stated in post #21 that someone doing the temp check at not even close range to there tranny manual will could have upwards of 500mL +++ of fluid variance which is ALOT and I am not telling people to do set there fluid levels at 200f when manual says 100f

I am just saying how if you followed a manual and it says to do it at 100f and you did it at 105f or 95f you are def fine as the volume won’t expand that much in 5f of variance to cause a considerable difference in fluid level

In post 21 I stated how the the fluid variance due to expansion at 80c and 20c could lead to a volume variance up 500mL ++

I never stated or never intended to mean that a 200f tranny fluid fluid would be the same volume as 80f. I stated that anyone who tries there best to get the tranny level as close to the manual temperature can sleep at night even if it wasn’t perfect to the T

Once again I mean no disrespect to you or anyone on this thread. I just feel as if someone doesn’t read my post in entirety could come to the wrong conclusion and I don’t want to be spreading misinformation when I stated all the facts.

I respectfully mean no harm with this reply

Then, I misunderstood your math assumptions. Is being off by 5F a big deal? No. On that we can agree.

But that's why there is a range, it's not a precise absolute value.

That said, I don't find that getting the Toyota done in range is particularly difficult. I do a complete flush, clean everything up, unpin the thermostat, and then set the level. I have to wait and watch the temp readout as it warms up, when it gets to the low end, undo the plug, let it drain, put the plug back in and I am done.

 

[apollo18]

Then, I misunderstood your math assumptions. Is being off by 5F a big deal? No. On that we can agree.

But that's why there is a range, it's not a precise absolute value.

That said, I don't find that getting the Toyota done in range is particularly difficult. I do a complete flush, clean everything up, unpin the thermostat, and then set the level. I have to wait and watch the temp readout as it warms up, when it gets to the low end, undo the plug, let it drain, put the plug back in and I am done.

Thank you! I totally agree the process on a Toyota is totally doable and I agree with you. The only reason I made this thread is so that newbies such as me and anyone else that may end up overthinking this procedure don’t freak out if they end up setting the fluid level at 117f rather then 110f or vice versa because even I don’t know how perfectly I set mine which is what got me thinking on the fluid expansion within a few Fahrenheit

 

[dubber09]

Overfilling can most def cause aeration and all that follows. Slight underfilling won't have I'll effects.

 

[JeffKeryk]

My procedure is not nearly as concise as some of the others. I get the car reasonably level, drain and measure, add about 1/4 quart more, start engine, use temp gun to check trans temp and let dribble at lowest point of range. This assumes fluid is perhaps a few degrees hotter than the hottest temp gun measurement taken from the pan surface.

I was a computer solutions architect. If you don't make the task as utterly fool proof as possible, you can expect bad results from your overall user base.
I believe the Toyota trans service, especially on our GS350, is too error prone.

 

[The Critic]

Overfilling can most def cause aeration and all that follows. Slight underfilling won't have I'll effects.

Just one OEM's opinion, but thought you may find this interesting:

 

[Leo99]

Between Apollo and Astro, i think the same thing is understood but perhaps different opinions on how tight the specs are. The fill level range is +/- ~60 mL out of a total fill of, I'm guessing, ~4000 mL at ~46°C. That is +/- 1.5%. That is a tight spec to me. It's tighter than specs on drug potency.

 

[Astro14]

Between Apollo and Astro, i think the same thing is understood but perhaps different opinions on how tight the specs are. The fill level range is +/- ~60 mL out of a total fill of, I'm guessing, ~4000 mL at ~46°C. That is +/- 1.5%. That is a tight spec to me. It's tighter than specs on drug potency.

Where are you getting your numbers?

60 ml? Tightest I’ve ever seen is the AW55 at 200 ml. Or +/- 100ml.

The NAG-1 is at least double that.

If you follow the factory procedure, and do it correctly, your margin of error will be well within the factory acceptable range.

Stop overthinking this.

Set it properly. Done.

It’s not the change in volume that is the issue, but the actual level in operation. You can’t forget that or hand-wave the calculation.

The only ones who need to calculate the tolerance and theoretical fluid expansion (which does not tell you the change in level - that calculation has to include the change in volume of the transmission case as level increases, and that hasn’t even been discussed yet) are the ones who devise their own methods.

I wish them luck.

 

[Rand]

my apologies if my original post was unclear. I believe there is a misunderstanding on what the moral/tldr of my post was

I don't mean to say for people to disregard any level checks. I am just saying how if someone is doing a level check on a toyota that has the level check procedure similar to mine, then even if they complete the level check a few fahrenheit too early or too late, it will make a negligible difference on the tranny fluid level.

In other words if a dipstick says to check the fluid level at 120F, however you ended up checking it at 115f or 125F it does not matter as long as you tried your best to check it close to 120F. checking the level at 200F would be a completely different story

Of course if we do my same calculation between 20c and 80c, even the math that i stated above would show a way greater variance of fluid (20c-80c would be almost half a quart of fluid expansion with a rough estimate).

just to clear any confusion, i do not mean or intend to mean for people to throw out the level check at all or be checking tranny levels's ice cold when they are supposed to be done piping hot.

I am just saying if you try your best and do the fluid check at close enough to the book's temperature, you will definitely be fine

I get 19.2oz of expansion. using .001 but its slightly lower than that so you could say .5qt or 16oz expansion is close to the 20c to 80c volume difference. on a 10qt system.

When I do mine.. I'll follow the procedure.
On the hyundai I'd may be tempted to drain and measure and refill at room temp.. since its impossible for me to get it level. IE 46oz ambient temp out.. 47oz back in