Tranny temps: how hot is too hot?

marcsbigfoot20b27 wrote:

Turtle n Peeps wrote:

marcsbigfoot20b27 wrote:
Yep, its not just about the fluid.......its also how much heat the seals can handle. One seal failure can mean totally disabled trans.

I worked at a transmission shop for 4 years (23 years ago) Seen lots of burned up units, some with wasted seals and clutch packs where the glue that holds the fiber to the steel was gone.

Anything over 225 for more than 5 minutes and I would pull over or add a bigger cooler. It doesn't matter if you have full synthetic that can handle 350 degrees if the seals melt.

My truck stock would get up to 210 going up the rim in AZ. Added a way bigger cooler and now it only gets to 160 max ever.

Do you think seal technology has stood still for 30 or 40 years? Just like fluid and everything else, the technology has increased immensely.


Mark; where are you at? Time to straighten some of these people out. :B Your phone is ringing!!

Well I am a sucker for information. Please do show some evidence of how hot is safe for regular and synthetic fluids and the seals in the transmissions. I would love to know the real answer.
Remember that not all of us tow with a 2015, some of us are still old school ~1995-2005

I posted earlier about my 2002 Chevy. 225 for five minutes is nowhere near to being a problem. From the owner's manual. That's good enough for me. Although 225 is around the number I look to stay under. Can't always hit that five minute mark though. I wait for top of hill, then pull over to cool down.

marcsbigfoot20b27 wrote:

Turtle n Peeps wrote:

marcsbigfoot20b27 wrote:
Yep, its not just about the fluid.......its also how much heat the seals can handle. One seal failure can mean totally disabled trans.

I worked at a transmission shop for 4 years (23 years ago) Seen lots of burned up units, some with wasted seals and clutch packs where the glue that holds the fiber to the steel was gone.

Anything over 225 for more than 5 minutes and I would pull over or add a bigger cooler. It doesn't matter if you have full synthetic that can handle 350 degrees if the seals melt.

My truck stock would get up to 210 going up the rim in AZ. Added a way bigger cooler and now it only gets to 160 max ever.

Do you think seal technology has stood still for 30 or 40 years? Just like fluid and everything else, the technology has increased immensely.


Mark; where are you at? Time to straighten some of these people out. :B Your phone is ringing!!

Well I am a sucker for information. Please do show some evidence of how hot is safe for regular and synthetic fluids and the seals in the transmissions. I would love to know the real answer.
Remember that not all of us tow with a 2015, some of us are still old school ~1995-2005

I'm not an expert on transmissions although I have built a few in my life. But I listen to them. If Mark shows up he can give you the facts you want.

The same goes for oil changes. Some still think 3K oil changes are necessary. This is just not the case. How do I know this? From lab reports that "prove" this is the case.

Some people go to the extreme and get their tranny too cold. This is as bad on things as too hot.

Like I said in my first post. If properly loaded, the OP will NEVER see anything close to 250F unless something is wrong so it's a mute point anyway.

Turtle n Peeps wrote:

marcsbigfoot20b27 wrote:
Yep, its not just about the fluid.......its also how much heat the seals can handle. One seal failure can mean totally disabled trans.

I worked at a transmission shop for 4 years (23 years ago) Seen lots of burned up units, some with wasted seals and clutch packs where the glue that holds the fiber to the steel was gone.

Anything over 225 for more than 5 minutes and I would pull over or add a bigger cooler. It doesn't matter if you have full synthetic that can handle 350 degrees if the seals melt.

My truck stock would get up to 210 going up the rim in AZ. Added a way bigger cooler and now it only gets to 160 max ever.

Do you think seal technology has stood still for 30 or 40 years? Just like fluid and everything else, the technology has increased immensely.


Mark; where are you at? Time to straighten some of these people out. :B Your phone is ringing!!

Well I am a sucker for information. Please do show some evidence of how hot is safe for regular and synthetic fluids and the seals in the transmissions. I would love to know the real answer.
Remember that not all of us tow with a 2015, some of us are still old school ~1995-2005

marcsbigfoot20b27 wrote:
Yep, its not just about the fluid.......its also how much heat the seals can handle. One seal failure can mean totally disabled trans.

I worked at a transmission shop for 4 years (23 years ago) Seen lots of burned up units, some with wasted seals and clutch packs where the glue that holds the fiber to the steel was gone.

Anything over 225 for more than 5 minutes and I would pull over or add a bigger cooler. It doesn't matter if you have full synthetic that can handle 350 degrees if the seals melt.

My truck stock would get up to 210 going up the rim in AZ. Added a way bigger cooler and now it only gets to 160 max ever.

Do you think seal technology has stood still for 30 or 40 years? Just like fluid and everything else, the technology has increased immensely.


Mark; where are you at? Time to straighten some of these people out. :B Your phone is ringing!!

Turtle n Peeps wrote:
All the experts will agree that 250 is no problem with modern fluids. At 270F you better start thinking about doing something.

It's a mute point anyway. If you are not over the GCVWR you won't even see close to these temps. 100 + ambient is a rule of thumb and close to what you should be seeing.

In short, with a modern truck you don't have to worry about tranny heat if loaded correctly.

X3.

The charts on the internet are OUTDATED...and do not apply to the modern synthetic ATF nearly every OEM is using today.

270-300 would be time to shut down and raise eyebrows as to how and why it got that hot.

Seals, clutches, bands...they are all designed to handle the heat today. We are not in the 80's or 90's.

Yep, its not just about the fluid.......its also how much heat the seals can handle. One seal failure can mean totally disabled trans.

I worked at a transmission shop for 4 years (23 years ago) Seen lots of burned up units, some with wasted seals and clutch packs where the glue that holds the fiber to the steel was gone.

Anything over 225 for more than 5 minutes and I would pull over or add a bigger cooler. It doesn't matter if you have full synthetic that can handle 350 degrees if the seals melt.

My truck stock would get up to 210 going up the rim in AZ. Added a way bigger cooler and now it only gets to 160 max ever.

Copied from another post about same thing...
Totally normal for 2014 GM. It has Dexron VI fluid which can handle much higher temps than previous fluids and IIRC, the factory will tell you normal temps for towing are 200-235 with a max of 265. In another article I read, In the February 2011 issue of Trailer Life magazine RV Clinic in response to a reader about the maximum transmission temperature allowed in a 2009 Chevy Silverado, the Tech Team had this response. “General Motors’ in-house towing team expert provided RV Clinic with this statement: The maximum allowable automatic transmission fluid temperature is dictated by the transmission oil itself. The oil begins to degrade significantly above 270 degrees Fahrenheit, so we design vehicles so that in all but the most extreme conditions, the fluid temperature in the transmission sump stays below 270 degrees F. We allow for up to 285 degrees F in extreme conditions (i.e. towing a trailer with combination loaded at GCWR in Death Valley). But for customer usage anywhere else in the country, even at GCWR, transmission sump temperature should stay well below 270 degrees F. Above this point, certain internal components, such as seals, begin to disintegrate rather quickly. Although newer synthetic fluids can withstand higher temperatures we still recommend this (270F) as a maximum temperature. "

First, for the newer transmissions, they use Dextron (sp?) VI fluid and can handle much higher temps.

Non towing I would expect below 200,
Towing, I would expect 200-235 with a max of 265.

I think they allow up to 275 for Death Valley customers that see higher ambient temps.

175 to not over 200 degrees seems to be recommended on the transmission temp charts I can find.

Search automatic transmission temperature.

TT lists at 5810lbs dry. My max GCWR is 15,000lbs. The GVWR is 6,800lbs so my total weight 12,610lbs plus gear.