I just did the ATF change on my F30 with a ZF8 gearbox. The book says to do the second stage of the procedure when the temperature is between 40 and 50 degrees C, but this has been very difficult in practice. After a drive with the engine hot, I arrived at the shop and had to wait several hours for it to cool down. Even so, after draining and refilling the oil, the temperature went back up very quickly - just a few minutes, while going through the gears. So the operation ended at 56 degrees, instead of the maximum 50. The mechanic says that's not an issue, but I wanted to double-check so I searched and found this thread. If my understanding is correct, you guys came to the same conclusion - that a few degrees won't make a significant difference in the resulting oil level.
Are we over exaggerating the perfect ATF fluid level? thermal expansion seems to think we are
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When I did my e90, the fluid temperature was 26c, so you definitely have a lot of time
It’s supposed to be between 30-50c
There were about 33 degrees outside, and probably the same in the shop. So pretty much zero chance of getting under that temp, even if the car was completely cold. Maybe if I left it overnight, but that was not an option. And when coming after driving a few km, the initial temp was way over that number.
The initial fill is supposed to be 30-40c, and the second stage when going through gears 40-50c, afaik.
The initial fill is supposed to be 30-40c, and the second stage when going through gears 40-50c, afaik.
You need to leave the car overnight. I usually like to start cold.
I’d agree that “precise” level is likely a tad overly worried about. My Elantra was a half quart under when I drained and refilled the trans initially. I do find that odd because it is precise enough in the instructions regarding measuring fluid level as to call out an exact cc amount draining at a specific temp range. I don’t know what the +/- is for level before you start to experience problems, and it’s likely different from transmission to transmission, but I was certainly glad that I decided to change it early (12k miles) instead of going the full 60k mile interval.
2017 Hyundai SantaFe. Dropped out warm transmission fluid. Filled with ambient temp new fluid. When fluid essentially quit coming out rather than an occasional drip I capped it and drove off. One year ago and operates perfectly.
That’s what I did on my C-HR cvt level check. I jumped the OBDII pins, started the engine and did the shifter dance. By then the D indicator was solidly lit, meaning it was already within the temp range. I barely had time to go under and drain the excess. The ambient was around 85F.
4WD
$50 site donor 2025
It’s easier to catch the temperature window starting cold …
4WD
$50 site donor 2025
I had a dream there was a dipstick with hot/cold marks - and inside a tube large enough to add the ATF under the hood …
Then I woke up in July ‘24
Then I woke up in July ‘24
30% is a big difference depending on what you’re measuring. You forgot you must multiply that difference by the expansion coefficient of .001 (assuming that’s correct). So you’re talking .03 units (30*F x .001 units/*F) of fluid. And that’s insignificant.
Either measure what came out and replace, or drain thoroughly and use OEM or Amsoil recommendations for replacement volume. Both ways will be close enough it won’t cause any issues.
I think I FINALLY figured out the variations in Tundra specs are the AB60F vs the whatever-750-whatever. I'm not a Toyota guy. The thing is almost no one mentions a transmission model -- they just throw out a temp range for a 2/2.5 Gen Tundra.
So yeah, details matter
its going to be impossible to find a consensus view on this issue. i am op and i had similar issue which warranted me to start this thread.
in my opinion and my scientific math calculations, there is negligible difference. albeit i havent done the calculation in forever, but if you finished at 6 celcius more which is comparable to my original calculation and we assume our tranny fills are pretty similar volume amount. the difference shouldn't / can't be more then 60ml and even that in my opinion is very very safely exaggerated. i believe the real value is probably around 30ml because we are assuming the expansion coefficient
nevertheless just put it into perspective, do you really think 4 tablespoons MAX would make or break ur tranny. 60ml is not much fluid especially when the pan probably holds 3-4 quarts atleast?. I am talking 60ml less or 60ml more, both ways
can't we assume that when we drive on a hill the fluid would pool up in whichever space and the tranny would assume its overfilled? and or underfilled depending on where the fluid gets used from, how about when we drive downhill? in other words i believe this variance is ALLOWED. and the only reason they give you that temp range is so that you set ur tranny fluid level at a temp close to the intended temp range.
for example if they didnt give a temp range then people could be filling the tranny with xyz amount of fluid cold vs xyz amount of fluid at 212F. that is a MAJOR difference in fluid temperature and expansion (much more then the 6c ) that you are looking at for yours
so after my starting this thread and thinking it thru. the manufacturer says 30-40 or 50-60 so that you end up setting the fluid around that range.
if they said 20c-100 c, then people would stretch the 100c to 120c or the 20c down to 10c and thats probably not what they want
so moral of story is get it as close as you can to what they said in the book (they said 50c for u, u got it done at 56) and sleep well atnight considering the fluid level cant change more then 30-60ml if you set it at 50c or 56c. it could be 30-60ml overfull or 30-60ml underfilled depending on if u set ur fluid level too hot or too cold but in the end it doesnt matter as long as its not like something significant like maybe 250ml or 500ml or etc
This is a funny one. Why are you all so concerned about just how much the fluid would change with the temperature?
The most important factor with this transmission fluid and temperature issue is, the ALUMINUM transmission case and other internal components will change in dimension as the temperature goes up, so its not just the fluid that can expand with temperature but also the container that is holding it. Also at operating temperature the fluid is going to drain off said parts and internals much better than when cold. So there is more to the oil level at a proper temperature deal than is thought.
The thing that gets me is, if the fluid amount is that critical, put it in a display on the screen. And the idea of a confined fill hole on the side of the trans vs a fill tube is just plain stupid. My GS350 is a great car, but c'mon Toyota.
It shouldn't be that hard. If you want users to perform a task correctly, make it simple. KISS.
I forgot, Toyota calls it lifetime fluid. Sheesh. What a load...
It shouldn't be that hard. If you want users to perform a task correctly, make it simple. KISS.
I forgot, Toyota calls it lifetime fluid. Sheesh. What a load...
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Right, you have to start with the car sitting over night to get the fluid at outside temperature
You have to keep in mind that DIYers are not really thought of when doing transmission maintenance, as most of them either won't change the fluid or have a shop do it.
I think if you can't do it right, then don't do it
You have to keep in mind that DIYers are not really thought of when doing transmission maintenance, as most of them either won't change the fluid or have a shop do it.
I think if you can't do it right, then don't do it
I see your point.
In computer programming, we call that "bad design".
Just my 2 cents.
WOW adding this seems to bring more food to thought, so would u say level doesn't need to be precise as much? or it does?
How about a simple sight glass on the side of the case with a line on the glass where the fill level should be? I mean, I know it’s futuristic but that’s like what, 1880s technology??
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