ATF levels, temperature dependent fill mark

[NismoNVT]

I was looking at the ATF level in various temperatures, on a vehicle that requires the vehicle to be checked warm and after a 5 minute mixed used period of driving.

As ATF temps increase, the level drops down. For instance after 5 minutes the level is near top, but after 50 minutes the level is at the low marker.

Which is correct?

 

[atikovi]

Most late models you check it within a prescribed temperature range as shown on the scan tool, by removing a plug on the pan. If it's overfilled, it will automatically drain to the correct level. If nothing comes out, you pump in fluid through that hole and observe as before.

 

[kschachn]

I have no idea what you’re asking here. As the temperature increases the fluid becomes less dense and the level increases.

Whenever you are checking the level you should always do it in strict observance of the method listed in the owner’s manual or FSM. That is the correct method.

 

[mattd]

The level will be highest at full operating temperature (excluding overheating).

 

[tasch72]

Hot fluid expands. On my 4r70w's, there is an area for checking when cold and for checking at operating temperature, with the latter appearing higher on the dipstick.

 

[NismoNVT]

Most late models you check it within a prescribed temperature range as shown on the scan tool, by removing a plug on the pan. If it's overfilled, it will automatically drain to the correct level. If nothing comes out, you pump in fluid through that hole and observe as before.

This vehicle is a relic, in a good sense. Its got a drain plug, filter, drain pain, a dipstick. Nothing fancy.

 

[kschachn]

This vehicle is a relic, in a good sense. Its got a drain plug, filter, drain pain, a dipstick. Nothing fancy.

Even so you must always check the level exactly how the manual states.

 

[NismoNVT]

I have no idea what you’re asking here. As the temperature increases the fluid becomes less dense and the level increases.

Whenever you are checking the level you should always do it in strict observance of the method listed in the owner’s manual or FSM. That is the correct method.

Physics I get, but this vehicle's behavior is baffling me.

The vehicle has a dipstick that has a rectangular box that indicates range (top of the range indicates FULL, below that range indicates low). The FSM says once upto to operating temp, fluid should be in the range. Add fluid if its below it.
The FSM mentioned operating temp can be accomplished by driving for 5 mins in urban environments.

When I measure after 5 minutes of urban driving i get the fluid level near the top of the range. However, checking it at various points on a long drive, I see the fluid level decreasing.

 

[kschachn]

5 minutes? My old BMW manual said a minimum of something like 30. Is the engine supposed to be running while you’re checking? Do you run it through all the gear selections before checking? In neutral or park?

Most are considered warmed up at some point after the temperature gauge reads normal. I can’t imagine a car that will do this in five minutes in any climate. If there is a full range then anywhere in the box is acceptable and it’s there to account for temperature variations.

What car is this and what year?

 

[demarpaint]

This is a chart I use to check the ATF level in my 08 Jeep Liberty. It shows how temperature impacts the ATF fluid level. I have a special dipstick along with this chart and a home made thermometer I insert into the fill tube to measure the temperature. In 5 minutes the ATF temperature is like a warm to hot bath.

 

[tcp71]

"A" is for checking cold fluid and "B" is for hot fluid on a 6R80 transmission. Hot fluid is always higher on the dipstick if you are checking hot and cold levels the same way.

A

 

[NismoNVT]

This is a chart I use to check the ATF level in my 08 Jeep Liberty. It shows how temperature impacts the ATF fluid level. I have a special dipstick along with this chart and a home made thermometer I insert into the fill tube to measure the temperature. In 5 minutes the ATF temperature is like a warm to hot bath.

View attachment 139314

Thats how I understand ATF dipstick behavior, but this vehicle will display target fill at 170F and then at 180F it indicates minimum fill.

I dont get it, it should technically taper off at operating temp.

 

[kschachn]

Thats how I understand ATF dipstick behavior, but this vehicle will display target fill at 170F and then at 180F it indicates minimum fill.

I dont get it, it should technically taper off at operating temp.

It indicates the maximum fill at the higher temperature, not minimum. Usually on most vehicles the minimum fill is only there so you don’t cause damage while starting the engine. Then once it is up to temperature you perform the actual check of the level. And what do you mean “by taper” off?

What car is this again? And what year? Either you’re not performing the check properly or you’re not reading the dipstick correctly. The behavior you’re describing is not possible if it is done properly.

 

[ctechbob]

This vehicle is a relic, in a good sense. Its got a drain plug, filter, drain pain, a dipstick. Nothing fancy.

There are plenty of us with NEW transmissions that wish they had your relic. I'd love to have a real dipstick, but the only option for the 10R80 is a $230 aftermarket unit, and that is a bit steep for my tastes.

 

[dubber09]

Let the car idle for a few mins after you take it for a long drive, then check level.

 

[Revving2Redline]

This is a chart I use to check the ATF level in my 08 Jeep Liberty. It shows how temperature impacts the ATF fluid level. I have a special dipstick along with this chart and a home made thermometer I insert into the fill tube to measure the temperature. In 5 minutes the ATF temperature is like a warm to hot bath.

View attachment 139314

Great visual. I try to check or siphon of fluids cold.

 

[kschachn]

Hey Nismo did you get this figured out? What vehicle is it and what year? I noticed you posting in a bunch of other threads, but never came back here to finish this one.

 

[The Critic]

This vehicle is a relic, in a good sense. Its got a drain plug, filter, drain pain, a dipstick. Nothing fancy.

Sounds like an older Subaru.