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I am considering installing a transmission cooler in my 2013 LTZ to help out with transmission temperature while pulling a small camper. I'm wondering what happens to the transmission oil temperature in the winter when the ambient temperatures get -20 degF . I would think too cold of oil temperature would be bad also.
 

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Don't think a trans cooler is going to make the temp of your trans fluid lower than normal operating temp in the winter, radiator should actually keep it warm. It should maintain a more constant temp. I am not a mechanic though and sure someone will chime in if I am incorrect.
 

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most automatics have trans coolers (especially trucks). it just takes longer for the fluid to warm up i would think. once you're driving it around the moving parts will warm the fluid up (as 12 LT said, the antifreeze may help a little since it will warm quicker than the trans fluid).
 

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I don't know what temps things run at these days but I know on my old Caprice/Roadmasters I liked to lower the coolant fan temps specifically because with the in radiator tranny fluid cooler it helped keep the tranny cooler. Granted fan temps don't impact highway temps since forward travel handles airflow, but this lowered in town coolant temps and therefore tranny temps a solid 20F.

The better plate style coolers actually are setup to bypass the core of the cooler when the fluid is cold, sold under a few brand names and they tout it as a feature so should be easy to find.

Can you use a bluetooth dongle and scanning app to see what your tranny temps are and if you need to do anything?

I have only barely dabbled with those apps to scan the wife's car not really familiar with all the functions viewable.
 

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I don't know what temps things run at these days but I know on my old Caprice/Roadmasters I liked to lower the coolant fan temps specifically because with the in radiator tranny fluid cooler it helped keep the tranny cooler. Granted fan temps don't impact highway temps since forward travel handles airflow, but this lowered in town coolant temps and therefore tranny temps a solid 20F.

The better plate style coolers actually are setup to bypass the core of the cooler when the fluid is cold, sold under a few brand names and they tout it as a feature so should be easy to find.

Can you use a bluetooth dongle and scanning app to see what your tranny temps are and if you need to do anything?

I have only barely dabbled with those apps to scan the wife's car not really familiar with all the functions viewable.
Thanks for that info. I will do more research. I like that idea of bypassing when cold. I'm just trying to get a grasp on how transmission cooling works. I had an experience pulling a very large camper with my 2015 Silverado K1500 in minus -15F and happened to check transmission temp via the dashboard and found it was running 255 deg. I couldn't imagine how with that cold outside temperature. I monitored it until it got to 260 and pulled over for about a half hour to cool. It was still at 230 degF or something like that even after the 1/2 hour wait. I have pulled that camper many times including ambient outdoor temps of 90F + and trans temp never went above 220 and typically 195 to 200F. My theory is that it being so cold my cab heater was on high continuous and probably provided enough cooling to keep engine at temp without needing to open the thermostat (or barely cracked) preventing any coolant circulation in the radiator preventing any heat transfer to the transmission cooler lines in the radiator. It actually did that exact thing a 2nd time a year later but my drive was much shorter and temp only came up to 235 but that high of temp never happens even in very hot weather. What do you think of my theory? Be kind! lol
 

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I don't know what temps things run at these days but I know on my old Caprice/Roadmasters I liked to lower the coolant fan temps specifically because with the in radiator tranny fluid cooler it helped keep the tranny cooler. Granted fan temps don't impact highway temps since forward travel handles airflow, but this lowered in town coolant temps and therefore tranny temps a solid 20F.

The better plate style coolers actually are setup to bypass the core of the cooler when the fluid is cold, sold under a few brand names and they tout it as a feature so should be easy to find.

Can you use a bluetooth dongle and scanning app to see what your tranny temps are and if you need to do anything?

I have only barely dabbled with those apps to scan the wife's car not really familiar with all the functions viewable.
Torque Pro will read the transmission temp if you enable the GM specific PIDs.

There are too many threads on this to just post one. Google "Torque Pro Transmission Temp Impala". This forum was the first hit with six threads listed.
 

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Thanks for that info. I will do more research. I like that idea of bypassing when cold. I'm just trying to get a grasp on how transmission cooling works. I had an experience pulling a very large camper with my 2015 Silverado K1500 in minus -15F and happened to check transmission temp via the dashboard and found it was running 255 deg. I couldn't imagine how with that cold outside temperature. I monitored it until it got to 260 and pulled over for about a half hour to cool. It was still at 230 degF or something like that even after the 1/2 hour wait. I have pulled that camper many times including ambient outdoor temps of 90F + and trans temp never went above 220 and typically 195 to 200F. My theory is that it being so cold my cab heater was on high continuous and probably provided enough cooling to keep engine at temp without needing to open the thermostat (or barely cracked) preventing any coolant circulation in the radiator preventing any heat transfer to the transmission cooler lines in the radiator. It actually did that exact thing a 2nd time a year later but my drive was much shorter and temp only came up to 235 but that high of temp never happens even in very hot weather. What do you think of my theory? Be kind! lol

Cold temps may have affected shifting patterns and torque converter lockup possibly keeping the torque converter unlocked a lot.
 

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You are a brave man to go camping in a trailer in -20F.

A lot of the answer to your question depends upon details you haven't provided:
- Are you planning to do the OEM cooler or an aftermarket one?
- How big (what is the surface area) of your cooler?
- Where exactly will you mount it? (can affect the amount of direct airflow it will or will not receive)
- If aftermarket, HOW will you be mounting it? (e.g., Will it be in direct contact with the A/C condenser with the zip-ties some aftermarket manufacturers provide?) For the record, this is an easy, but less-than-ideal installation method for airflow.
- Does it have a built-in thermostat to bypass the cooler during cold temps?
- What is the year-round climate where you reside? (Meaning, are you potentially exposed to -20F for months at a time, or just transiently?)
- How often do you plan to be towing something?

The thermodynamic efficiency of a transmission cooler increases as the temperature drops. Most liquid cooled engine thermostats control/maintain a drivetrain operating temperature of 195F (the coolant temperature at which the thermostat allows coolant to enter the radiator rather than recirculate within the engine alone. Transmission oil temperatures (especially when towing) can well exceed 195F.

On standard passenger vehicles without supplemental transmission coolers, it is not an unusual practice in cold parts of the snowbelt (e.g., upper peninsula MI, MN, the Dakotas, etc.) to block all or part of the radiator just to make certain you car reaches and stays at operating temperature during sustained, extreme (sub-zero) cold spells. In extremely low temperatures (read: sub-zero), you MIGHT need to block airflow to the supplemental cooler with a piece of cardboard, IF you are not towing a trailer.

A lot of this comes from experience and the wisdom of others who live in the area and know how to adjust vehicle cooling to the seasonal climate. For above zero temps and "normal" (e.g., non-towing) use, you might not need to do anything beyond allowing the vehicle to adequately warm-up for a few minutes prior to beginning driving.

Much of the above are generalizations and your individual situation/circumstances may vary. Best of luck.
 

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Here are the 3 types of atf coolers rated by efficiency and price from lowest to highest: tube & fin, plate & fin and stacked plate. Some have built-in fans (which kick on with high atf temps) and t-stats (which bypass the cooler in cold temps). Here are the 3 most popular cooler brands: B&M SuperCoolers (stacked plate), Hayden and Derale. Personally, I'd go with a B&M SuperCooler for your application.
 

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Here are the 3 types of atf coolers rated by efficiency and price from lowest to highest: tube & fin, plate & fin and stacked plate. Some have built-in fans (which kick on with high atf temps) and t-stats (which bypass the cooler in cold temps). Here are the 3 most popular cooler brands: B&M SuperCoolers (stacked plate), Hayden and Derale. Personally, I'd go with a B&M SuperCooler for your application.
The Long Tru-Cool Low Pressure Drop LPD4739 oil coolers have a built in thermal bypass so they don't cool oil that's not up to temp. This is the AUX cooling unit I installed in the transmission cooler lines in My Silverado and Impala.

If you run the oil flow through the radiator and then the AUX cooler you'll come up to temp fairly quickly and a regulated AUX cooler will only cool the oil if it needs to be cooled.
 

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^+1. In my old Fords, I always left the radiator cooler in the loop with the aux. cooler, some say to bypass it.
 
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