Transmission too cold?

[itsbo1313]

So it’s been cold lately and my tranny hasn't got over 105 degree’s. Should I be concerned?

 

[swathdiver]

So it’s been cold lately and my tranny hasn't got over 105 degree’s. Should I be concerned?

Nope. Mine rarely gets to minimum temps which is 158 for the HOT fill check. Still going strong!

 

[Donnie Yukonie]

Nope transmissions are essentially a big hydrualic pump. being a bit "cold" is better than too hot. heats the worst enemy of any trans.

 

[Doubeleive]

i have mine modified to run cool and it will sometimes run that low, no problems

 

[itsbo1313]

Okay, thanks.

 

[Miami-Dade]

Nope transmissions are essentially a big hydrualic pump. Being a bit "cold" is better than too hot. Heats the worst enemy of any trans.

I just had my transmission replaced last week due to the heat killing it.

 

[itsbo1313]

I had mine rebuilt before we moved out of California. 30k miles later I’m debating a tranny flush or drain and fill.

 

[Charlie207]

It's been stupid-cold around here lately, and yesterday the ATF temp didn't hit 100* F (per the dashboard digital gauge) until almost 45 minutes of constant driving. For the first 20 mins it was at like 30*F and felt like molasses.

 

[SNES Avalanche]

I had mine rebuilt before we moved out of California. 30k miles later I’m debating a tranny flush or drain and fill.

Drain and fill.

 

[Geotrash]

I've done a ton of reading about this topic over the past year, and so far I haven't found a single person who knows precisely why GM (and other manufacturers) explicitly recommend a minimum continuous operating temperature for transmission fluid. For the 6L80E for example, it's 150ºF. Some speculate that it's for fuel economy reasons, and others speculate that cooler fluid being more viscous, can increase wear in some components. Not only does it appear in GM service literature, but some transmissions ship from the factory with thermostats designed to allow the fluid to warm up to operating temperature faster before sending fluid through the external cooler.

For some reason seemingly unknown to the universe of shade-tree mechanics and forum participants, there is a minimum recommended operating temperature for transmission fluid. Anyone know a GM (or other) powertrain engineer who can answer that question for us? Without that key insight, we're all just speculating about ideal transmission temps, or if running them cooler than 150ºF has any consequences worth managing differently.

 

[donjetman]

Anyone know a GM (or other) powertrain engineer who can answer that question for us? Without that key insight, we're all just speculating about ideal transmission temps, or if running them cooler than 150ºF has any consequences worth managing differently.

Call Tom Johnson of "JG Lubricant Services" @ 877-971-7799 ext 2 or [email protected] . I've talked to him several times on the phone. Tom Johnson is President and CoOwner of JG Lubricant Services, LLC. Tom holds a BS in Mechanical Engineering Technology from Purdue University and has over 30 years of experience in the bearing, automotive and transmission industries. Prior to forming JG Lubricant Services, Tom was the Transmission Fluids Engineer for Allison Transmission, Inc.2 Tom served in that capacity for the final 20 years of his long career before retiring in 2009. While serving as the Transmission Fluids Engineer, Tom worked with all of the global oil and additive companies. He wrote most of Allison Transmission’s lubricant specifications (including the groundbreaking TES-295 specification). Tom directed and managed testing and approval of hundreds of transmission fluid formulations for Allison Transmission and served as a member of the GM Engine Oil Committee and was a key member of the GM Automatic Transmission Fluid (ATF) Committee.

 

[itsbo1313]

Drain and fill.

Even with only 30k on the rebuild? Is there ever a condition where a flush is the right answer?

 

[pwtr02ss]

I had mine rebuilt before we moved out of California. 30k miles later I’m debating a tranny flush or drain and fill.

Do it. And the filter

 

[Charlie207]

Even with only 30k on the rebuild? Is there ever a condition where a flush is the right answer?

Only if you can absolutely guarantee there is no FOD unaccounted for inside the transmission.

 

[Doubeleive]

I had mine rebuilt before we moved out of California. 30k miles later I’m debating a tranny flush or drain and fill.

whenever mine have been done it's a stipulation that it be flushed annually for the warranty to remain in effect so obviously there is a reason why. I make it a habit to do it anyway for all fluid except the differential those seem to be ok going a bit further. I went to change the front after a year and the fluid out looked like it just came out of the jug.

 

[Doubeleive]

It's been stupid-cold around here lately, and yesterday the ATF temp didn't hit 100* F (per the dashboard digital gauge) until almost 45 minutes of constant driving. For the first 20 mins it was at like 30*F and felt like molasses.

drive faster lol

 

[Charlie207]

drive faster lol

It's easier to just rest my left foot on the brake pedal.

 

[Bob2C]

Nope. Mine rarely gets to minimum temps which is 158 for the HOT fill check. Still going strong!

I replaced my original thermostat for the new one which lowers the temp to around 150. Would the fluid show a lower fill mark from when I was checking while at the original operating temp of say 195? I haven’t had time to check on level ground.

 

[swathdiver]

I replaced my original thermostat for the new one which lowers the temp to around 150. Would the fluid show a lower fill mark from when I was checking while at the original operating temp of say 195? I haven’t had time to check on level ground.

Yes, like this: