How to properly check transmission fluid

[diyjake]

What is the proper temperature to check the ATF level? I checked my ATF level when it was 15 degrees F out and there was barely anything on the dipstick so a few days later I checked it again when the the temperature was 40 degrees and it was higher up on the dipstick but still a lower than the lowest cold mart so I drove it for 10-11 miles and checked the level again and at the point fluid was over the high mark on the hot side. My car is always parked outside.

My question is what is the ideal temperature to get an accurate reading on the cold mark of the dipstick? Also what is the correct hot temperature?

 

[kschachn]

Every car or manufacturer is different. Follow what says in your owner's manual.

 

[StevieC]

Originally Posted by kschachn
Every car or manufacturer is different. Follow what says in your owner's manual.

This.. Some you need special dipsticks and a scan tool along with a temperature / measurement chart.

Others you need the ATF at a specific temperature and let excess spill out of a straw like in Toyota's

 

[diyjake]

This is on my 09 camry, it has the basic transmission dipstick, it has a cold low and high and a hot low and high on the dipstick. I looked in the owner's manual and I didn't find anything on how to service the automatic transmission. I probably missed it although the engine oil, brake fluid, power steering info was right there.

 

[The Critic]

You need to drive it for about 20-25 min at highway speeds. On Toyota's with an A/T Fluid dipstick, the A/T Fluid Temp needs to be > 170F in order for the "hot marks" to be applicable.

 

[diyjake]

Originally Posted by The Critic
You need to drive it for about 20-25 min at highway speeds. On Toyota's with an A/T Fluid dipstick, the A/T Fluid Temp needs to be > 170F in order for the "hot marks" to be applicable.


I appreciate the info.

 

[Oro_O]

Do you have a 5spd or 6spd?

I have found this 5spd (U150e) tricky to check; I have no experience w/the 6.

With the 5, the only reliable procedure I found was to start it from cold and rely upon the cold marks. If run, the splash seemed to get into the tube and bias the reading too high.

 

[diyjake]

I have the 5 speed. The problem is when I check it cold the level really changes depending on the outside temperature.

 

[The Critic]

Originally Posted by diyjake
I have the 5 speed. The problem is when I check it cold the level really changes depending on the outside temperature.

Never check it cold.

I only use the cold marks to confirm that there is enough fluid to test drive the car. Any fluid level adjustment needs to be done when the a/t fluid is hot.

Also, remember, coolant temp is not the same as a/t fluid temp.

 

[69GTX]

Some makes you can check ATF cold just fine. My Lincoln Continentals are very consistent when I check them cold. Always high up on the dip stick....at the exact same place. Checked it dozens of times over the years.....same reading.

 

[Oro_O]

Originally Posted by The Critic
Originally Posted by diyjake
I have the 5 speed. The problem is when I check it cold the level really changes depending on the outside temperature.

Never check it cold.


The problem is with this transmission, the high temp marks are unreliable - it's a quirk. I believe it's because the cooler return line causes enough pan splash near the fill tube to negate it.

The thermal expansion rate of ATF is really not that large. I read once the rate and it translates to 10qts at 30C = 10.5qts at 100C.

On this transmission, anything over 40F, I start it, shift through the gears and let it warm a little. It will warm some from transfer via the flexplate, but not a lot. then use the cold marks. If you are not shifting through the gears first, then it may be because the valve body is draining down some and changing the fill reading.

 

[Hall]

I realize you're dealing with a Toyota but just as an example of the inconsistencies with reading ATF levels, my Infiniti field service manual says 86-122º is "cold" and 149º is "hot". It's not clear how high the temperature can be during this reading unless the transmission cooler (??) keeps it at or below 149ºF.

 

[slacktide_bitog]

I've never found any ATF dipstick to be accurate, except for Honda, which uses a different design for their transmissions and you check the fluid with the car off.

 

[ccs368]

For the older Toyotas with a conventional dip stick with hot and cold range, my biggest mistake after performing a transmission flush was I checked the level with the car engine off. The car engine is suppose to be running at idle when you measure the atf level with the dip stick. You may want to check out what is the necessary procedure with your particular transmission.

I did the routine service during summer when it was probably around 75F-80F. After refilling to what I thought was correct, I ran through the gears for like 15 sec and the fluid level was between the high and low COLD mark with engine off. Then I drove the car for around 20 minutes and rechecked level and now it was at the high HOT mark. I drove my car this way for 6 months with no issues or any DTC lights if there even was any. At the 6 month interval, it was winter in NY and the ambient was probably 35F-40F. The car would start to slip between 1st and 2nd gear at cold starts. After about 5 minutes driving, the slipping was not as severe or went away. This symptom was consistent and repeatable and frankly I was worried that changing the OEM ATF at 125K ruined the transmission.

So after reading on internet that I performed the level check improperly 6 months ago, I remeasured with the engine idling this time. The dip stick did not even register anything at COLD marks. I drove the car for 20 minutes and now I see a level at low COLD mark. So to make a long story short, I had to add 1.5qts of the Toyota T-IV fluid until I was able to get a proper HOT level with the engine idling.

I have driven the car for 1 year since correcting the level and no problems whatsoever. Funny that no warnings was given when driving underfilled for almost 6 months because the expanded ATF was probably borderline acceptable during the summer months and then reared its ugly head when the ambient temperature dropped during winter months.

 

[diyjake]

Good thing your transmission didn't take a crap.

 

[dave1251]

I believe the best advice anyone can give you is to follow your service or owners manual because the procedure can be unique to each vehicle.