Transmission Temperature Gauge, Can I Rely On It?

Amazonica

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I have a 2019 JLUR, auto, 3.6L, factory tow package, and am towing near max. I know consistent high temps harm transmission fluid, shortening transmission life and want to avoid that Two questions; is the digital “Trans Temp” gauge range accurate? And what is the actual “danger” redline number for the JL 8 sp auto?

I’ve been towing on I-70 Colorado and Utah, at around 60 mph, hilly mountainous terrain, elevation between 4000-8000 ft. Air temps 50-60 and the trans gauge has stayed around 204, briefly once 218. If you’ve looked at the gauge, it has an “analog” look (the arc with ticks) and displays numbers below. The “redline” portion to the right of the arc on the gauge appears too far even when the numbers showed temp of 218. Is that just for looks? Is there an annunciation when the trans temp gets into damaging heat?

This thing tows great, stops great (I have brake controller and trailer brakes), just don’t want to harm my transmission.





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Almost

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Basically anything above 220 is bad. If you are seeing constant temps at around 200 I would change it at half the interval shown in the book. And if the book says lifetime fill they're full of it.

"The ideal fluid temperature is under 175 degrees, but as fluid ages it starts to break down and lose its capacity to cool down the transmission. This is when transmission overheating occurs. At 220 degrees, varnish forms. At 240 degrees, seals start to harden."
 
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Amazonica

Amazonica

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Thank you Almost. That was the info I needed. It also tells me that the graphic for the trans temp gauge is just for show.
 

WranglerMan

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Tranny temp will usually run close to oil temp unless you have an additional cooler so 175-225 is going to be the range and as stated if it’s running 200+ when not under a load it may be time to consider changing
 
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Amazonica

Amazonica

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Thank you WranglerMan. When I'm not towing, it usually stays just under 200. Although driving 75mph in a strong headwind recently kept it around 210.
 

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