Hi guys. I have noticed that my transmission temperature is about 80 degrees higher than the ambient temperature outside. This is after the tranny has warmed up, and is running down interstate about 70 mph. So when it is 50 outside, the tranny temp runs about 130. When it's 90, the tranny runs about 170. Anyways, is this about average what you guys see? My truck is a 2008 Silverado Z-71, with the 5.3 engine. I don't use it for towing. I'm running Maxlife ATF in it. Just curious on what temps you guys see in your vehicles. Thanks
Automatic transmission temperature
- Thread starter Chevys_n_Hawgs
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I think you're right on the money. I usually see 80-100 over the ambient temp as well, more toward 100 higher if I'm towing in my 03 2500HD
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Never stopped to figure that one out. That's probably because I'm used to hearing ambient temperatures in Canada in Celcius, and my tranny temp readings are in Farenheit. Some quick math now, and I figure under normal conditions, the spread on mine is much lower.
My Scangauge II report my trans temps to be 220-230F under normal driving conditions in my Mazda3. This is even with a B&M trans cooler! The highest I've seen is 243F while driving in a neighborhood for an extended period of time. I'm just assuming that these are the temps this trans was designed to run at.
While I can't speak for the OP's exact transmission, one of the designers of the Ford 4R70W, used in millions of F150s and Crown Vics, says that every 20° above 170°F cuts the life of the fluid in half. I take that to mean that right around 170°F is ideal for that RWD transmission.
FWD transaxles seem to run higher, but I don't know much about the temperature aspect i.e. what's "normal".
FWD transaxles seem to run higher, but I don't know much about the temperature aspect i.e. what's "normal".
125F when driving on the freeway
154F highest in stop and go driving
Had the temp go as high to 200F with a full load in the bed, going uphill in 3rd gear following behind a semi truck at low speed.
This is on a toyota tundra v8 with the A340 (AW4) transmission with stock ATF cooler. Running DexVI fluid.
154F highest in stop and go driving
Had the temp go as high to 200F with a full load in the bed, going uphill in 3rd gear following behind a semi truck at low speed.
This is on a toyota tundra v8 with the A340 (AW4) transmission with stock ATF cooler. Running DexVI fluid.
That sounds about right. When up to full operating temp, my truck's transmission runs about 100* over ambient temp, a little less when the t-stat for the cooler opens up. It maxes out at a little over 190* F on a hot summer day with a small trailer. Lately 150* F has been typical once warmed up.
Originally Posted By: CharlieJ
My Scangauge II report my trans temps to be 220-230F under normal driving conditions in my Mazda3. This is even with a B&M trans cooler! The highest I've seen is 243F while driving in a neighborhood for an extended period of time. I'm just assuming that these are the temps this trans was designed to run at.
The trans may be designed OK, but it's the the fluid that is not meant for those high temps.
My Scangauge II report my trans temps to be 220-230F under normal driving conditions in my Mazda3. This is even with a B&M trans cooler! The highest I've seen is 243F while driving in a neighborhood for an extended period of time. I'm just assuming that these are the temps this trans was designed to run at.
The trans may be designed OK, but it's the the fluid that is not meant for those high temps.
What temp it "too high" when it comes to ATF?
I've noticed the 90F diffrence on average as well. During the summer my trans runs 192-198F on average.
Originally Posted By: Chevys_n_Hawgs
What temp it "too high" when it comes to ATF?
As was mentioned earlier in this thread (and I have read similarly), 170 degrees seems to be the "sweet spot" for transmission fluid for long life. Anything above about 200 and you're cooking the fluid.
What temp it "too high" when it comes to ATF?
As was mentioned earlier in this thread (and I have read similarly), 170 degrees seems to be the "sweet spot" for transmission fluid for long life. Anything above about 200 and you're cooking the fluid.
Originally Posted By: Chevys_n_Hawgs
What temp it "too high" when it comes to ATF?
Oxidation increases remarkably above 200F but it's time at temperature that counts for more than a spike. The longer the oil stays at that high temp, the faster it degrades. Most oils can take 250F easily... some even 300F... but their life gets drastically shortened the longer they remain at that temp.
There are spots in an automatic where the temp is momentarily very high while the bulk temp is fairly low. There can be a 100F difference in temp, or more, between the pan and the converter, for example.
Basically, if you were to monitor the pan temp and see 150-170, you'd be OK. If the pan is seeing 200 plus, imagine what the converter is seeing. Converter temp drops remarkably once the converter clutch locks (most modern transmissions have) so that tends to keep converter temp close to the pan temp. The converter is locked most of the time on the freeway
In town, with lots of starts and stops, not only are you running the converter unlocked a lot, you are cooking the trans oil every time it shifts. There is oil in the clutches and they slip a little every time the apply and with oil being in there, that oil is momentarily subjected to some high heat.
Also, at higher oil temps, synthetic base ATF oxidizes more slowly
So, as you can see, there is no one size fit's all answer. If you see regular temps under 200F, call it good. You should get good oil life. If you see regular temps higher, the OCI needs to be shorter.
What temp it "too high" when it comes to ATF?
Oxidation increases remarkably above 200F but it's time at temperature that counts for more than a spike. The longer the oil stays at that high temp, the faster it degrades. Most oils can take 250F easily... some even 300F... but their life gets drastically shortened the longer they remain at that temp.
There are spots in an automatic where the temp is momentarily very high while the bulk temp is fairly low. There can be a 100F difference in temp, or more, between the pan and the converter, for example.
Basically, if you were to monitor the pan temp and see 150-170, you'd be OK. If the pan is seeing 200 plus, imagine what the converter is seeing. Converter temp drops remarkably once the converter clutch locks (most modern transmissions have) so that tends to keep converter temp close to the pan temp. The converter is locked most of the time on the freeway
In town, with lots of starts and stops, not only are you running the converter unlocked a lot, you are cooking the trans oil every time it shifts. There is oil in the clutches and they slip a little every time the apply and with oil being in there, that oil is momentarily subjected to some high heat.
Also, at higher oil temps, synthetic base ATF oxidizes more slowly
So, as you can see, there is no one size fit's all answer. If you see regular temps under 200F, call it good. You should get good oil life. If you see regular temps higher, the OCI needs to be shorter.
Originally Posted By: CharlieJ
My Scangauge II report my trans temps to be 220-230F under normal driving conditions in my Mazda3. This is even with a B&M trans cooler! The highest I've seen is 243F while driving in a neighborhood for an extended period of time. I'm just assuming that these are the temps this trans was designed to run at.
Thats way too hot for me!
My Scangauge II report my trans temps to be 220-230F under normal driving conditions in my Mazda3. This is even with a B&M trans cooler! The highest I've seen is 243F while driving in a neighborhood for an extended period of time. I'm just assuming that these are the temps this trans was designed to run at.
Thats way too hot for me!
It is tremendously important to note WHERE the temp is sampled.
All parts of the trans do not operate at exactly the same temp, and the output to the cooler is a little bit hotter than the return line!
All parts of the trans do not operate at exactly the same temp, and the output to the cooler is a little bit hotter than the return line!
I have a 2011 F150 FX4 with the Ecoboost engine. The productivity screen shows trans temps and they held in a very tight range regardless of the season. The temp range runs from 195 to 203 ( the highest I've ever seen it) .
I had a chance to talk to some Ford engineers at an event held here in Houston last year and I posed the question we are talking about. According to Ford's power train engineers this is the desired temp range. The trans was designed with these temps in mind and their reasons were: 1) fuel economy ; the trans uses a low viscosity fluid to start with and then heats it to 200 degrees and 2) shift quality; there's no doubt that Mercon LV fluid at 200 degrees will be in a reliable cst range over the life of the trans however long that may be....
I stressed my old schools values of trans temps below 160 for max life of both trannie and fluid and he stressed that both the fluid and trans were built to do this by design. The LV fluid appears to me to be a grp III base oil but I'm not as good as others at reading the mfgr 's spec sheets. Any one care to weigh in on all this?
I had a chance to talk to some Ford engineers at an event held here in Houston last year and I posed the question we are talking about. According to Ford's power train engineers this is the desired temp range. The trans was designed with these temps in mind and their reasons were: 1) fuel economy ; the trans uses a low viscosity fluid to start with and then heats it to 200 degrees and 2) shift quality; there's no doubt that Mercon LV fluid at 200 degrees will be in a reliable cst range over the life of the trans however long that may be....
I stressed my old schools values of trans temps below 160 for max life of both trannie and fluid and he stressed that both the fluid and trans were built to do this by design. The LV fluid appears to me to be a grp III base oil but I'm not as good as others at reading the mfgr 's spec sheets. Any one care to weigh in on all this?
Kestas
Staff member
From my notes on transmission lube:
Temp...Life
175....100K
195.....50K
220.....25K (common operating temp for most vehicles)
240.....10K
260......5K
300......1K
This is likely for regular fluid and not synthetic.
Temp...Life
175....100K
195.....50K
220.....25K (common operating temp for most vehicles)
240.....10K
260......5K
300......1K
This is likely for regular fluid and not synthetic.
Originally Posted By: SteveSRT8
It is tremendously important to note WHERE the temp is sampled.
All parts of the trans do not operate at exactly the same temp, and the output to the cooler is a little bit hotter than the return line!
Exactly right. Many sensors are in the pan and are taking a reading of the fluid after it has gone through the cooler. Once it gets picked up and goes into the convertor, it can gain a lot of heat very quickly.
It is tremendously important to note WHERE the temp is sampled.
All parts of the trans do not operate at exactly the same temp, and the output to the cooler is a little bit hotter than the return line!
Exactly right. Many sensors are in the pan and are taking a reading of the fluid after it has gone through the cooler. Once it gets picked up and goes into the convertor, it can gain a lot of heat very quickly.
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