Toyota Corolla Determining Proper Transmission Fluid Level

[ToyotaLover67]

Hello. I drive a 2012 Toyota Corolla LE.

I'm having some difficulty sussing out the correct level for my transmission fluid.

I've read online that you want to fill it, and check the level when the car is warm, not hot. Meaning you start it, and let it idle for 5-10 minutes.

Others say they simply drive it around for same amount of time, park, and check the level that way.

Both are markedly different in terms of the readings I get.

Idling for 10 minutes gets me a reading at the high cold mark.

Driving it around for a bit, parking, and then checking even after 20 seconds yields Full, while a minute or two, or five yields a reading of low high, which makes more sense in this regard, but is still far from the high to low cold point on the dipstick.

I need to know which method I should be relying on.

Checking it after 5 to 10 minute idling, or after 5 to 10 minutes driving it around.

Both yield drastically different readings.

 

[JHZR2]

What does the owners manual say? Or the FSM?

@clinebarger provided a photo of a manual,that showed marked differences in dipstick readings depending upon temperatures, when I was servicing my 47RE. I’d suspect any AT will be similar.

 

[proveitwithdata]

Hello. I drive a 2012 Toyota Corolla LE.

I'm having some difficulty sussing out the correct level for my transmission fluid.

I've read online that you want to fill it, and check the level when the car is warm, not hot. Meaning you start it, and let it idle for 5-10 minutes.

Others say they simply drive it around for same amount of time, park, and check the level that way.

Both are markedly different in terms of the readings I get.

Idling for 10 minutes gets me a reading at the high cold mark.

Driving it around for a bit, parking, and then checking even after 20 seconds yields Full, while a minute or two, or five yields a reading of low high, which makes more sense in this regard, but is still far from the high to low cold point on the dipstick.

I need to know which method I should be relying on.

Checking it after 5 to 10 minute idling, or after 5 to 10 minutes driving it around.

Both yield drastically different readings.

dipstick on tranny, cold mini after starting car, and shifting through gears. hot mini after a nice 30 minute mixed use drive.

If no dipstick, then you need to get the atf to the set temp and check the level at the fill plug?

 

[BrendanC]

every auto transmission i’ve ever done, drain and replace 3/4 of the fluid amount that you drained. start the engine and fill until on the “cold” or in the middle of the range on the dipstick. get in the car and cycle from reverse, drive, 1, 2 or low etc multiple times then go back to park. check the level and fill until back at the cold or in the middle of the range. take for a drive making sure to let the transmission shift through all gears and lock the torque converter. check fluid again and fill until at the “hot” mark or at or near full range on dipstick. have done this same procedure atleast 100 times without fail.

 

[kschachn]

What does the owners manual say? Or the FSM?

@clinebarger provided a photo of a manual,that showed marked differences in dipstick readings depending upon temperatures, when I was servicing my 47RE. I’d suspect any AT will be similar.

This right here. Many cars have a somewhat different procedure and I would follow it exactly.

 

[The Critic]

In the absence of a scan tool that can relay fluid temp info, I would use the cold marks on the dipstick and only fill to the min mark.

 

[FowVay]

Right out of the book. The U341E transmission is identical. Original poster didn't mention details so I looked up both.

 

[The Critic]

Right out of the book. The U341E transmission is identical. Original poster didn't mention details so I looked up both.

View attachment 203153

Fluid temperature is the key here - not the coolant temp.

Getting the trans fluid temp to 70-80C can take a while and isn’t easily achieved.

 

[FowVay]

um, that is the fluid temperature. That's the procedure for checking the "transmission fluid". Nothing mentions coolant temperature in the manual procedure. Am I missing something?

 

[kschachn]

Just do what the manual says and repost back.

 

[The Critic]

um, that is the fluid temperature. That's the procedure for checking the "transmission fluid". Nothing mentions coolant temperature in the manual procedure. Am I missing something?

It is a common misconception of DIYers that fluid temp = coolant temp. Just wanted to point that out.

 

[ToyotaLover67]

Well, I have a scan tool that tells me the engine temp. Not sure if that's supposed to be my guide. Kinda don't think that reflect the trans fluid temp.

 

[kschachn]

Well, I have a scan tool that tells me the engine temp. Not sure if that's supposed to be my guide. Kinda don't think that reflect the trans fluid temp.

No. Just follow the procedure given above from the manual. It's part of why there is a range of "OK" on the stick.

 

[ToyotaLover67]

No. Just follow the procedure given above from the manual. It's part of why there is a range of "OK" on the stick.

I don't have the original owners manual, but I do have the Haynes Manual. I will check it to see if the procedure is in there, and let you know.

 

[ToyotaLover67]

No. Just follow the procedure given above from the manual. It's part of why there is a range of "OK" on the stick.

The Haynes manual doesn't go into that much detail. It simply says to fill it slowly, constantly checking while it is in idle, then to shift through the gears when at the high cold mark. Beyond that it doesn't say.

Am wondering if I should drive it, park, switch through the gears, and then immediately check it.

I let it idle earlier for 10 minutes, then went through the gears, then let it idle 5 more minutes, then checked level. The coolant temp was at 186F, and the trans fluid level was at high cold mark.

I am guessing this is just a starting point, and have to drive it to get the Hot level correct.

 

[The Critic]

The Haynes manual doesn't go into that much detail. It simply says to fill it slowly, constantly checking while it is in idle, then to shift through the gears when at the high cold mark. Beyond that it doesn't say.

Am wondering if I should drive it, park, switch through the gears, and then immediately check it.

I let it idle earlier for 10 minutes, then went through the gears, then let it idle 5 more minutes, then checked level. The coolant temp was at 186F, and the trans fluid level was at high cold mark.

I am guessing this is just a starting point, and have to drive it to get the Hot level correct.

Like I said, it can take a long time for the trans fluid temp to reach the specified range.

I would just use the cold marks and set the fluid level to the min cold mark after the vehicle has sat overnight.

 

[ccs368]

My biggest mistake with my ‘03 Corolla is I measured the transmission fluid level with the engine off. So ultimately this gave me an under fill even though the level showed correct whether it was cold or fully warmed up. I screwed up. I also see no reference in my owners manual on how to properly check so I understand the concern. What I do since it’s more meaningful to me to visually see change is I measure the dip stick right after sitting overnight engine stone cold with engine off. It may show full in cold region on the dip stick. Then I measure with engine running after a minute going through the gears and see the level likely dropping significantly from the first measurement. Then I take a drive for at least 30 minutes with highway/city and repeat the measurements. You should have 4 readings. The reading after the long drive with engine running is the most meaningful to my year, make, and model on level driveway. Seems like a lot of work but I like to observe fluid expansion and how the level changes which gives me the best understanding. I also know there’s nothing but OE type IV fluid and no mixture of other brands so also gives me more ability to predict consistency that way.

 

[ToyotaLover67]

My biggest mistake with my ‘03 Corolla is I measured the transmission fluid level with the engine off. So ultimately this gave me an under fill even though the level showed correct whether it was cold or fully warmed up. I screwed up. I also see no reference in my owners manual on how to properly check so I understand the concern. What I do since it’s more meaningful to me to visually see change is I measure the dip stick right after sitting overnight engine stone cold with engine off. It may show full in cold region on the dip stick. Then I measure with engine running after a minute going through the gears and see the level likely dropping significantly from the first measurement. Then I take a drive for at least 30 minutes with highway/city and repeat the measurements. You should have 4 readings. The reading after the long drive with engine running is the most meaningful to my year, make, and model on level driveway. Seems like a lot of work but I like to observe fluid expansion and how the level changes which gives me the best understanding. I also know there’s nothing but OE type IV fluid and no mixture of other brands so also gives me more ability to predict consistency that way.

Well, I let it idle, went through the gears, and it was at the high cold mark. Maybe that's where it should be if you start it from cold, and even it idles 15 minutes it doesn't expand much. I don't know.

I will need to change it soon anyhow, as I am on change 6 of 10 to fully flush the system, so when I go to buy some more trans fluid from the dealership I will ask if they know the proper procedure.

 

[ccs368]

Well, I let it idle, went through the gears, and it was at the high cold mark. Maybe that's where it should be if you start it from cold, and even it idles 15 minutes it doesn't expand much. I don't know.

I will need to change it soon anyhow, as I am on change 6 of 10 to fully flush the system, so when I go to buy some more trans fluid from the dealership I will ask if they know the proper procedure.

I wouldn’t be surprised what you measured because imho, idling doesn’t really replicate the heat getting into the transmission without shifting through the city, fluid pumping through the atf cooler, etc so go for a really good spin and measure again. At least it isn’t low like my mistake where the symptoms only showed during the cold winter temps 4 months later and the auto transmission just kept slipping until warmed up. You’re on the right track.

 

[ToyotaLover67]

Right out of the book. The U341E transmission is identical. Original poster didn't mention details so I looked up both.

View attachment 203153

I assume the temp is that of the trans fluid? I'm currently using a fixd obd2 tool with blue tooth that connects to their app on my phone, and it only has an option for reading coolant temperate. Is there an inexpensive scanner tool that can also read transmission fluid temp? Does the 2012 Corolla LE even have a transmission fluid temp sensor? This method seems most accurate, but without the ability to read the trans fluid temp it doesn't help me much. Can I use one of those point and shoot temp scanner tools to read the metal of the trans fluid drain pan? Would that even give an accurate reading? The metal on the outside would be cooler than the fluid inside I would think.