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Hi everyone.

Does anyone know what is the normal operation transmission Temp? I'm getting between 174F to 185F only highway driving with out any load on the truck. The truck only have 21,500 miles on her.

Thanks
 

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2021 GMC Sierra Denali CC 4WD Ultimate 6.2L
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The owners manual states the the fluid should be at normal operating temperature, which is 82°C to 93°C (180°F to 200°F) when checking the ATF level.

I traveled about 500 miles last Friday and hauled back about 500 lbs of oil. Temps were in the high 80's to low 90's. I keep a eye on the my trans temp gauge just to see what it would run at in the heat and it stayed in the 170's. Normal driving. I changed mine over the synthetic at very low miles and now have about 13,000+.
 

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went to disneyland a few weeks ago. 80degrees outside up and down hills my trans stayed around 175
 

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Weird. Mine stays in the 140 - 155 range in normal driving. Up to 160-165 when I am towing the boat. Ambient temps in MN have been around 75 - 85 degrees. Seems like mine is running cooler than most?
 

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And mine stays in the middle range (I forget- is that right around 200?). It's almost always a tick below the middle mark, but it has poked past it (like when I was trying to get unstuck in the winter :().

However, we've got different axles\transmissions\engines, so is it really apples-apples?
 

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I have been on the road since June 6th towing 7000 lbs trailer on hauls around 400 km a day and mine is usually around 65 to 75 and goes up to about 79 to 80 when I am pulling a lot of big hills, I am glad Big Silverado started this topic so I feel better about my temperature.
 

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My rear axle is a 3.42 and I made a mistake typing, mine stayed in the 150 range, not 170 as I listed and I was on cruise control most all the time I could.

Towing or hauling
Somewhere I was reading that if you are towing you should use tow haul mode for several reasons. It over-rides the alternator fuel economy mode and allows more power to charge the battery when a trailer is connected. If you do not you could have battery run down problems. It also allows the cooling fans to run longer to cool the engine and transmission heat. Everyone just thinks its for trans shifting but that's not the only feature of tow/haul mode.

Vehicles with an automatic transmission have a Tow/Haul Mode. The Tow/Haul Mode adjusts
the transmission shift pattern to reduce shift cycling, providing increased performance, vehicle control, and transmission cooling when towing or hauling heavy loads.
If charging a remote (non-vehicle) battery, press the Tow/Haul Mode button, if equipped, located at the end of the shift lever. This will boost the vehicle system voltage and properly charge the battery. If the trailer is too light for Tow/Haul Mode, or the vehicle is not equipped with Tow/Haul, turn on the headlamps as a second way to boost the vehicle system and charge the battery.
 

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Interesting, Mike. I plan on doing some long distance towing this summer. Given that fully loaded with the boat, I will only be at about 5,000 lbs, I thought i would go with out tow/haul. Now I think I may consider using it.

However, my boat has surge brakes, not electric, and my headlights are always on, due to the HID relay. So there again, I may not need it?
 

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Towing the trailer today (90F outside temp), the tranny temp stayed at about 190 the whole time, except when I was on the freeway. It would drop to about 160 or 150... is this because of the increased air going through the radiator?
 

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It was 86 here today. I had to do some stop/go driving. The tranny got as high as 171, but that's it. I checked the fluid. All full and looks great.
I do notice that the temp drops when i a on the highway. Not sure if that's due to increased airflow. I figured it was due to the fact that the torque converter is locked. Should be less heat generated when converter is locked.
 

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2007 k2500 gmc z71 duramax-I bought 4 monthes ago. Trany temp. was fine until I got into 99+ degree weather and was using air cond.--temp. climed to over 216 and I turned off a.c.--climed again when back on. Took it to dealer to have it checked out and have trany fluid and filter service done. They found loose or damaged air damper or diverter [directs air to heat exchanger]----- problem now seems fixed. The trany seemed to shift like it was in cold op mode when it was at 216 but I never got d.i.c. message or over heat warning. Does this make sense to anyone? have I solved the problem? only have about 20 miles on it since fix so am keeping fingers crossed----
 

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Just got back from vacation, where we towed the boat, gear, and 4 people about 500 miles. I am not guessing a bit, but would say I was towing about 5,000 total. I kept a pretty close eye on my transmission temperatures, especially as I hit some rolling hills in Northern MN. Transmission temp gauge never exceeded 180. It would usually drop down to the 160's on flat ground. Outside air temp was around 80 degrees. I did not use the tow/haul mode at all, as it held 6th gear very well on the flat ground. Considering I have seen temps in the 170's without towing, it would appear that the tranny can handle towing pretty well.
 

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Not nearly as far, approximately 150+ miles towing 4 ATVs on trailer (easily +-3000 lbs) and some gear this past Friday, temp in the 80's, from Lake Superior sea level 602 ft to approximately 1800 ft in elevation (Then we rode the ATV's about 80 miles). I used Tow/Haul just for the heck of it all for the 150 miles never turning it off. Never once felt the trailer (did last year not using it), the alt gage stayed charging all the time. At 55-60 mph the rpm's were about 2100 and AFM was engaging, no downshifting at all which it did last year all the time driving the same route. Also noticed the grade braking when slowing, needed little brakes to slow or stop.

All in all while you may tow with ease w/o T/H mode, the truck drives better IMHO. It does not appear I used more fuel in T/H and actually think I used less due to no down shifting when coming to slight grades.

Actually have something similar to T/H on the CTS but they call it sport/performance mode.

PS-I also watched the trans temp, 154 deg was the highest I saw.
 

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Mike, your tranny, transfer case, and differentials are full of AMSoil, right? How much did that stuff drop your tranny temps?

I'm in the process of changing out my drivetrain fluids, so I hope to see some improvement once I do all of the major fluids changes.
 

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Thanks Mike. I was trying to save some gas by not using tow/haul. I will try it next time. Thanks!
 

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starspangled6.0 said:
Mike, your tranny, transfer case, and differentials are full of AMSoil, right? How much did that stuff drop your tranny temps?

I'm in the process of changing out my drivetrain fluids, so I hope to see some improvement once I do all of the major fluids changes.
Yes, 0W-30 in the engine, Severe Gear 75W-90 in both axles, Low Viscosity ATF in the transmission and transfer case and synthetic PS fluid in the PS. 100% synthetic fluids as I been doing for over 20 yrs.

Its a proven fact that synthetic engine oils and drive train fluids improve fuel economy but its hard to quantify. Many variables affect mileage such as: tire inflation, the type of fuel, weather, elevation, the speed at which you drive, the gear in which you drive, the speed with which you accelerate, engine maintenance, excessive idling, the grade of motor oil you use, etc.

It hard to say on my truck because I changed everything out at around 1,000 miles on the truck. Where you should see improvements is in colder weather use.
 

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If you plan to put on a plow I would suggest you pay close attention to the transmission and have it checked out by a professional before installing a plow. Have the pan dropped and checked for cleanliness, should be nothing settled in the pan. You do not want any surprises when plowing that could have been avoided if you had known trans problems were on the horizon. When I put the plow on the 92 back in 2002, I did that. The pan was as clean as new and the trans showed no signs of any wear. So I had them R&R with synthetic in the trans (complete purge of all ATF) and both axles. Had I found anything laying in the pan, that would been a sign of wear and the trans might not have lasted the first winter plowing. Actually I did that even before buying the plow because the truck has 60,000 miles put on it by the original owner who as it turned out did not abuse the transmission.

Every winter I get calls from guys with plows telling me how they had to have the trans rebuilt and they were told to change it to synthetic before they over-heat the trans again, from plowing. For instance, one logger with his Furd had been puking ATF out the dipstick because he plows the roads to the logging operation in 4x4 high range (too slow in low range) and the trans would over-heat and ATF will come out the dipstick tube. The trans shop rebuilt it (lot of hard miles on the truck) but the very first time he plowed, puked some ATF again. They sent him down to me to get 5 gallons of ATF and they changed it out for him. That was 3 yrs ago and he says, it has not puked one drop of ATF since.
 

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I run between 160-185 (depending on how hard i drive and highway or back roads) on days around 85-90 degrees. I do have a tranny cooler on my truck as well, so it might be different than yours. Also, I have a digital temp gauge so I can get a very accurate reading and I find that the stock gauges are very inaccurate compared to digital. The factory gauge seems to display a higher temp than the more accurate digital gauge I have, so you're probably running 4-9 degrees cooler than the factory gauge displays.
 

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I have been driving my 2011 5.3L around Houston all summer in heat 90-100F. I have been keeping a close eye on the trans temp and the highest I have seen is 185F. That includes a few highway trips to Austin and College Station. I have not done much towing with it, and I am curious to see what it will run with a load behind it.
 
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