How long to wait and method to check tranny fluid?

[Oldmoparguy1]

Originally Posted By: SwedishRider
I know traditional ATF should be checked when hot and vehicle is level and idling. But how long after one stops and idles a vehicle should one check the dipstick for an accurate reading?

And also, I tend to stop the car, put it in park, then work my way down through all the gears with my foot on the brake, and then come back up to park (with the thesis that it moves all the fluid around fully in the transmission before I check it). Is that good or bad practice (or doesn't make a difference either way)?

I need to make sure the readings I'm getting are accurate. Thanks!

It would help to know which type and model of car. Some AT's are picky about fluid level, others, not so much. Case in point, my older model mopars all have dipsticks marked for cold, warm and hot fluid levels and are not fussy about being a pint over or under.

 

[SwedishRider]

No worries Ducman- apology accepted.

I'm not having issues with the transmission per se, but I am getting readings that are higher than the cross-hatch section of the dipstick. I'm trying to get it to within the acceptable level range.

But no, the transmission isn't acting up (that I can notice anyway). I think I'm going to check the level after a 20+ minute drive one more time, and if the level reads high, I'll use my vacuum extractor to pull out some fluid, and then check again.

 

[Rhymingmechanic]

The manual for my Pontiac Vibe (Toyota transmission) gives instructions to shift through the gears and then let the engine idle in park for 3-5 minutes before checking. It also gives a specific "normal" operating temp that will result in the proper reading, and cautions against checking when the fluid is too hot--like after driving at high speeds or in heavy traffic in hot weather.

I would check the ATF at different times, to get a sense of how the dipstick reads relative to fluid expansion. Check first thing in the morning to see if it's in the "Cold" range. Where is it after a short drive, then a longer trip or lots of stop and go? Watching how the level changes with temperature should help you determine whether your fluid is high enough to worry about.

 

[SwedishRider]

Originally Posted By: Rhymingmechanic
The manual for my Pontiac Vibe (Toyota transmission) gives instructions to shift through the gears and then let the engine idle in park for 3-5 minutes before checking. It also gives a specific "normal" operating temp that will result in the proper reading, and cautions against checking when the fluid is too hot--like after driving at high speeds or in heavy traffic in hot weather.

I would check the ATF at different times, to get a sense of how the dipstick reads relative to fluid expansion. Check first thing in the morning to see if it's in the "Cold" range. Where is it after a short drive, then a longer trip or lots of stop and go? Watching how the level changes with temperature should help you determine whether your fluid is high enough to worry about.


That's interesting. Each time I checked my transmission with a high reading, it was after driving on the highway for 20+ minutes. Maybe that is "too hot" for testing and throwing off the correct measurement.

 

[slacktide_bitog]

Transmission dipsticks are almost never accurate anyway. The only exception I know of is Honda, but their automatic transmissions are very different from everybody else.

In a Honda, you check the ATF with the car *off* after getting it warmed up and waiting a minute or two.

 

[SwedishRider]

I think we may be closing in on an answer..

I ran the truck for about 5-10 minutes on back roads to go get a bite to eat, and then drove it back the same 5-10 minutes. I then went through the gears, and let it idle in park on level ground for 4-5 minutes.

Result? Fluid was in the crosshatches EXACTLY in the center. I checked it again to confirm the measurement, and it was dead on the money the second time as well.

I guess highway driving for extended periods does mess with the measurement of the fluid levels. I'll keep an eye on it, but I think this mystery may be solved.