Transmission cooler inside radiator

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thompsoj22

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08 yukon denali xl1500 6.2, on a recent trip at freeway speeds with an outside temp of 43f the trans temp never went above 78f. on a trip while towing our 4,500lb travel trailer up a steep grade with an outside temp of 85f the trans hit 210f. i do have the factory trans cooler but can see it is not thermostatically controlled. i will add the aftermarket cooler but i think ill go with a thermostat. Anyone know if it is detrimental to run a automatic trans with cold fluid temps for an extended period of time?
 

Doubeleive

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08 yukon denali xl1500 6.2, on a recent trip at freeway speeds with an outside temp of 43f the trans temp never went above 78f. on a trip while towing our 4,500lb travel trailer up a steep grade with an outside temp of 85f the trans hit 210f. i do have the factory trans cooler but can see it is not thermostatically controlled. i will add the aftermarket cooler but i think ill go with a thermostat. Anyone know if it is detrimental to run a automatic trans with cold fluid temps for an extended period of time?
that doesn't sound right mine will hit 76 just idling in the driveway and I have the deep pan and truecool, it may take a few minutes to warm up on the freeway but definitely does not stay that low
 

BG1988

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that doesn't sound right mine will hit 76 just idling in the driveway and I have the deep pan and truecool, it may take a few minutes to warm up on the freeway but definitely does not stay that low
Honestly with dexron 6 there is very low minimum temp

viscosity of Dexron VI transmission fluid is thin even at 72F

it's the same viscosity as warmed up Dexron III

seems the actual minimum temperature is 72F recommend temp
but it does not really matter much
lower temp = longer life




MAX continuous operating temp is 212/100C but the transmission will not last very long at that temp

minimum operation temperature is Negative -45C after that it becomes too thick to use/a solid
 
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Doubeleive

Wes
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what is the temp yours runs at on the highway not towing with your cooler? Just driving 70 mph or so. Mine seems to stay in the 165-175 range 60-75 degrees outside temp fairly flat terrain Fort Worth to Austin, TX.
about 126-134 I watch it all the time, I also have the B&M deep trans pan on there.
 

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