Can transmission fluid be too cold?

[Patman]

I know they say heat is a killer of auto trannies, but is it bad if the fluid doesn't get super hot?

This evening coming home from work it was only 28F outside, and even after one hour of rush hour traffic, my trans fluid only got up to 167F. For the first half of the drive it wasn't even above 150F.

Is this harmful in any way? I'm curious as to whether or not moisture gets into the trans fluid that needs to be removed by hotter temps? (such as with engine oil)

 

[1maniac]

patman,

I put external coolers on all my AT's and never gave it a second thought. I decided to do an UOA and learned that, indeed, water forms in the ATF from cold temps and short trips. I since have blocked off the external cooler in the winter. Problem solved. In the summer I make sure to get out and burn it off via a long trip.

I suspect that a thermostat controlled cooler is the way to go.
That'll be in my next car.

UOA's are a valuable tool.

 

[Patman]

On the plus side, I do drive my car long distances pretty much everytime I start it. My commute to and from work is typically 45-60min.

I don't have an aftermarket cooler on the trans, just the factory one.

 

[heyjay]

Pat:

Now you know why I believe in winter fronts in winter!

I put a huge 12x16 cooler and a B&M remote mount filter/temp gage on my 1984 Ford F-150 with C6 auto. With over 500,000km and routine servicing, the C6 is solid.

However, in temps much colder than 0 F / -18 C, the gage would never leave the bottom of the peg. With the winter front, it would struggle to reach 120 F.

On the other hand, driving at 80 MPH on I-80 between Laramie and Rock Springs, WY in August, the trans temp gage rarely went over 170 F.

 

[Patman]

quote:

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Originally posted by heyjay:


On the other hand, driving at 80 MPH on I-80 between Laramie and Rock Springs, WY in August, the trans temp gage rarely went over 170 F.

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I was impressed with the way my factory trans cooler worked this summer because even in 90F weather in stop and go traffic for an hour, I would not see the trans go above 185F. The only time I'd see it go beyond that would be if I was making a lot of full throttle runs in a row. But even then I never ever saw it go above 220.

 

[unDummy]

quote:

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Originally posted by Patman:
I know they say heat is a killer of auto trannies, but is it bad if the fluid doesn't get super hot?
This evening coming home from work it was only 28F outside, and even after one hour of rush hour traffic, my trans fluid only got up to 167F. For the first half of the drive it wasn't even above 150F.
Is this harmful in any way? I'm curious as to whether or not moisture gets into the trans fluid that needs to be removed by hotter temps? (such as with engine oil)

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Not harmful. If anything, your temperatures are perfect. Moisture will evaporate with those long drives so it shouldn't be an issue. Don't forget that water in a glass at room temperature will evaporate so the time:temp needs to be addressed. Your 45min-1hr drive is plenty.

Some electronic transmissions need temp to allow proper shift patterns. Usually 110-130F will allow most transmissions to shift properly.

Also, you need to consider instant vs average temp. Even if you are measuring only 150-167 degrees. There are areas in the transmission that are hotter and colder.

 

[mechtech]

A transmission doesn't have to deal with the same moisture problems as an engine. Water is a by-product of burning gasoline, and can have internal coolant leaks.
Be happy!

 

[MaximaGuy]

quote:

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Originally posted by unDummy:

quote:

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Originally posted by Patman:
I know they say heat is a killer of auto trannies, but is it bad if the fluid doesn't get super hot?
This evening coming home from work it was only 28F outside, and even after one hour of rush hour traffic, my trans fluid only got up to 167F. For the first half of the drive it wasn't even above 150F.
Is this harmful in any way? I'm curious as to whether or not moisture gets into the trans fluid that needs to be removed by hotter temps? (such as with engine oil)

---

Not harmful. If anything, your temperatures are perfect. Moisture will evaporate with those long drives so it shouldn't be an issue. Don't forget that water in a glass at room temperature will evaporate so the time:temp needs to be addressed. Your 45min-1hr drive is plenty.

Some electronic transmissions need temp to allow proper shift patterns. Usually 110-130F will allow most transmissions to shift properly.

Also, you need to consider instant vs average temp. Even if you are measuring only 150-167 degrees. There are areas in the transmission that are hotter and colder.

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I have an external cooler on my Maxima and my ATF would not get to even 100F even after a couple of miles of driving. Now in the winters, I doubt it even crosses 100F after a long drive. The shifts are very smooth -- the least to say, but should I be concerned if the ATF does not get to the 125-150 range!!!

 

[1 FMF]

all I can say is good thing you don't have the 6-speed. I have digital temp gauge (for oil) with a sender also on the drain plug of the tranny.
In the summer, on my usual drive to work of 20-40 min, 15 miles, trans fluid would run around 130F. On my trip to upstate NY, 350 miles @ 70mph, it ran 160-170F.
Now with the weather between 25-40F outside and the car garaged overnight even, trans fluid hasn't gone over 110F yet. On the cold mornings, it runs below 100F my whole drive.

Since GM specs Dex3 tranny fluid for the M6 and it's fill for life, if you have faith in [GM] engineers then that would say condensation is a non issue with trans fluid.

 

[Etcetera]

I visted this site today to ask this very same question.

I have a 2001 F-250 V10 Auto 4x4. Friday I took a 90 mile trip to pick up some stuff. When I arrived temp was about 125 F. Left a couple hours later and it got up to about 135 when I parked. Factory cooler and a deep sump pan. Most of that trip was locked in OD, so not much heat will be generated. It was about 60F out.

After reading looks like I'm OK. Towing in the summer I've yet to hit 190F.

Maxima Guy: It will take at least 5 miles before you hit 100. My daily drive is 10 miles on the streets. The needle usually makes it to the first mark, 100f, about half way.
Eric

 

[MaximaGuy]

One question that is kind of stupid but anyway shall ask the folks who have external coolers ..

1) Is the reading on the dipstick during hot/cold reflective of the amt of ATF in the cooler? The dipstick reading during hot is a little above the hot spec -- this isn't overfill right!!!

2) Sometimes when I move the stick from Drive to Park it feels like the stick free falls into park with a mild "thug" and when this happens I need to give it extra pressure to move from Park to Gear and with the same thug -- kind of metals touching each other... This does not happen if the shift from gear to park was smooth -- wierd cold clutch metals...

The second question is kind of mechanical but this is my first winter with the cooler (didn't happen last winters without the cooler). Is the viscosity of the ATF not enough to provide lubrication to disengage the auto trannmission pin.

 

[DJ]

One of the tranny parts vendors I have worked with got into the buissiness while living in Alaska and he is very insistant that it is possible to overcool a tranny. Think about it tranny fluid is designed to work at tempature, many stock applications tie it to the coolant which may hit 220F before the fans turn on. That is a bit too hot by almost all account but do you really think running it 100F below that is a good idea? Temp sender location/accuracy has to be considered here too. In an engine just because there is no condensation in the oil with a fresh oil change would you go out and wail on the motor cold, no the oil has to be brought up to operating temp first, same with the tranny the fluid is designed to be used at a temp above ambient temps, most knowledgable builders recommend 160-180 as ideal. I know some guys with well modified cars say they have experianced slippage if they run with the fluid under 160, the power just makes the symptoms of the too cold fluid more apparent. There are some better external tranny coolers like Tru-cool and B&M(same pieces different brands) that sell plate style coolers with a viscosity based bypass that is supposed to act like a thermostat of sorts.

 

[ULVER]

I put a tranny cooler rated for a mobile home towing a car.

I think it's like 30,000 pounds GVW. Stacked plate designs, with a stat, have you covered in winter, and covered in the summer. The tranny shop that services all the Atlanta police cars told me this: Put the largest SOB on your car, you can find & fit.

 

[unDummy]

Maximaguy, Nissans usually won't lock the TC if the temp isn't high enough. If your torque converter is locking up, then the temp is hot enough. How are you measuring the temp? where is the sender? brand?
It takes my Altima at least 10 minutes and about 5 miles of driving before my trans temp is hot enough(cold start/outside temp 30f) to allow TC lockup on the highway without any aftermarket trans coolers.
I think that your shifter needs to be lubed. And, apply the parking brake prior to shifting into Park. It seems that you might be rolling while shifting into park causing the difficult next shift into drive. Shift into drive prior to releasing the parking brake.
And, a cooler won't make it any colder than cold. That means, the '1st start shift' shouldn't be any different whether you have a cooler or not.
Flush your ATF. Nissans are tough on ATF. Use a synthetic or OEM fluid.

 

[MaximaGuy]

quote:

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Originally posted by unDummy:
Maximaguy, Nissans usually won't lock the TC if the temp isn't high enough. If your torque converter is locking up, then the temp is hot enough. How are you measuring the temp? where is the sender? brand?
It takes my Altima at least 10 minutes and about 5 miles of driving before my trans temp is hot enough(cold start/outside temp 30f) to allow TC lockup on the highway without any aftermarket trans coolers.
I think that your shifter needs to be lubed. And, apply the parking brake prior to shifting into Park. It seems that you might be rolling while shifting into park causing the difficult next shift into drive. Shift into drive prior to releasing the parking brake.
And, a cooler won't make it any colder than cold. That means, the '1st start shift' shouldn't be any different whether you have a cooler or not.
Flush your ATF. Nissans are tough on ATF. Use a synthetic or OEM fluid.

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I agree with u that it may not have anything to do with the aftermaket cooler in the path. I flushed my tranny with Chevron DexronIII + Lubegard Black a month ago. I think the shifter may need lubrication but haven't done that myself, I shall check for documentation on the web or http://forums.maxima.org/...