I'm still trying to get my head around why Toyota is so finicky about measuring ATF at operating temps.
How much does ATF expand from volume at 70F to volume at 125F?
- Thread starter andyd
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You could easily measure this on a stove in a glass graduated cylinder on a hot plate.
Agreed on finicky, but i dont thing it is all that crucial. Over fill by a half, do the procedure, at 105F, there should be a slowed stream toward trickle at the check plug.
Agreed on finicky, but i dont thing it is all that crucial. Over fill by a half, do the procedure, at 105F, there should be a slowed stream toward trickle at the check plug.
It's the same with Mercedes, you have to have it "precisely" at 45C, otherwise I guess it just immediately goes thermonuclear
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It will expand by about 0.75 fluid ounces per quart.
The reasons Toyota is so finicky about the temperature is because it measures the fluid by the amount that will overflow. When you remove the check plug, the hole is not directly at the bottom of the pan - there's a tube that goes up. When the correct amount of oil heats to the correct temperature, it overflows ever so slightly and gets into the tube to drip out. If the temp is too low, it will not get high enough to overflow in the tube. If it's too hot, too much will overflow.
The reasons Toyota is so finicky about the temperature is because it measures the fluid by the amount that will overflow. When you remove the check plug, the hole is not directly at the bottom of the pan - there's a tube that goes up. When the correct amount of oil heats to the correct temperature, it overflows ever so slightly and gets into the tube to drip out. If the temp is too low, it will not get high enough to overflow in the tube. If it's too hot, too much will overflow.
GON
$175 Site Donor 2026
Anecdotal evidence-
Recently I acquired a 2015 Toyota Tundra with 147k miles. No history of transmission fluid exchange.
I did two spills and fills. The Tundra sat overnight before the spill and fill. Both time the tundra spilled a bit over four liters into a catch container.
Today I did another spill and fill. Only difference, the Tundra was outside overnight, and I pulled the Tundra into the garage for the spill and fill. The spill only dropped three liters. Outside temperature during the spill and fill today was 95 degrees Fahrenheit. Why the reduction from four liters to three liters? Increase in transmission temperature from outside air, and under one minute of engine running? Increase in just outside air? Or, simply the transmission slowly leaks fluid from places like the torque converter into the transmission oil pan after extended sitting/ non use?
The Tundra is in the garage tonight, I will do another spill and fill in the morning with the transmission cold, and see if four, three, or another quantity spills.
Recently I acquired a 2015 Toyota Tundra with 147k miles. No history of transmission fluid exchange.
I did two spills and fills. The Tundra sat overnight before the spill and fill. Both time the tundra spilled a bit over four liters into a catch container.
Today I did another spill and fill. Only difference, the Tundra was outside overnight, and I pulled the Tundra into the garage for the spill and fill. The spill only dropped three liters. Outside temperature during the spill and fill today was 95 degrees Fahrenheit. Why the reduction from four liters to three liters? Increase in transmission temperature from outside air, and under one minute of engine running? Increase in just outside air? Or, simply the transmission slowly leaks fluid from places like the torque converter into the transmission oil pan after extended sitting/ non use?
The Tundra is in the garage tonight, I will do another spill and fill in the morning with the transmission cold, and see if four, three, or another quantity spills.
It's not just Toyota, but many modern transmissions now have a fancy fill chart with a max/min table to keep the fluid level in range of. Really don't know why they had to overcomplicate things when old school transmissions had a simple dip stick and as long as you were in the full mark, then you were fine. Just like with engine oil, I doubt that overfilling a transmission slightly is harmful for it.
CleanSump
Site Donor 2026
I hate to burst anyone's OCD, but I've been doing a Mercedes and a BMW by the temp method for 18 years and it's not critical.
It's not hard. The temp doesn't have to be right on the dot, just close in the neighborhood. No need to consult a chart, view pictures of what the correct drip looks like, or count the drips per second.
You can read what the computer tells you, use an infrared thermometer, and even a candy thermometer works. Does anyone actually think the dealerships sweat it that hard?
It's not hard. The temp doesn't have to be right on the dot, just close in the neighborhood. No need to consult a chart, view pictures of what the correct drip looks like, or count the drips per second.
You can read what the computer tells you, use an infrared thermometer, and even a candy thermometer works. Does anyone actually think the dealerships sweat it that hard?
GON
$175 Site Donor 2026
Yes,
Just did another spill and fill this morning.
Fourth spill and fill completed.
The big question, to remove the pan or not. I inspected the bolts this morning, no sign of corrosion/ rust in the threads. I read about the bolts breaking during removal and make sure one " knows what they are exposing themselves to". The spill and fill may be fine, but it looks more likely than less likely the fluid was never exchanged prior to my purchase (147k miles).
Honestly, I’d skip dropping the pan unless you’re changing the filter. If you do decide, as mentioned prior, hit the bolts with some penetrating oil first. Also might help to tighten them just a tad before trying to loosen them.
On a side note, LubeGard Platinum has my 110K mile Sequoia shifting like new again after 2 prior drain and fills.
On a side note, LubeGard Platinum has my 110K mile Sequoia shifting like new again after 2 prior drain and fills.
ATF doesn't expand any more than engine oil in terms of volume. But while the engine oil level on the dipstick doesn't increase massively when hot, it does in an auto box. The reason for the difference is that the engine oil in the sump is just that a container of oil with not much else in it. The ATF sump on the other hand has huge lumps of metal submerged in it so that any expansion of volume is exagerated in terms of the effect that it has on the level.
Exactly. I consider those precision instruments and don't like risking loss or forgetting one as I cannot stand an incomplete hex key set. Thus began my search for something more readily available and expendable.
I've ordered plenty of individual hex keys but always from machinist supply like Enco (RIP) or MSC. It's easier to source old scrap brake parts than an individual replacement hex key.
JHZR2
Staff member
Does the FSM have a graphic?
@clinebarger shared an image that was helpful for my 47RE.
@clinebarger shared an image that was helpful for my 47RE.
My 47RE is shifting beautifully, but can be a little bit sluggish to start off in the very cold. I know per the FSM and from @clinebarger that the fluid has to be checked fully hot and in neutral. I did it today, and it looks great, but a little low. This was after driving about 25 miles on the interstate in 32F weather.
I can’t find reference to how much fluid is needed between the crosshatch, in the OM or the FSM. The OM has good instructions, but not even a pic of the dipstick, while the FSM has a bit of info but not any quantity.
Does anyone know the...
Does anyone know the...
It definitely expands when hot. I got the transmission in my cherokee so hot, it was pushing fluid out of the dipstick 
