Dexron VI-how hot is too hot?

[dwendt44]

Took Grand Prix to dealer as torque converter seemed to be hunting some after lock-up at 45 mph.
They adjusted something in the computer that increased the line pressure. Seems to have fixed the 'hunting' but now trans. fluid get pretty hot if driven for any length of time.
WAS holding about 135-140°; NOW it's hovering about 170° and it's not even August yet.
Is that too hot?
Views/opinions?

 

[S2500Dog]

Normal temperatures for any automatic transmissions is cut-off at 175 degrees. With 170 degrees at stake now, you are really pushing your ATF fluid to the limits. I would recommend seeking a professional mechanic or AT technician and have things checked before they become an devastating diaster.

 

[Colt45ws]

Depends on where you are measuring. 175* sounds fine to me. Heck, the thermostat on my trans cooler does not even open until 180F so my pan fluid temp runs 160-180 all the time under normal service; itll hit 200F pulling a hill with the torque converter unlocked. I would say more like 225-250 is the limit for short bursts, but below 200 is fine for continuous service.

 

[crazyoildude]

We only do engines here and not transmissions but if it always ran 135-140 and now after the dealer did something to the computer it runs 30 degrees hotter something is wrong..
Heat is one of the worst things for a transmission i put coolers on everything for that reason..

 

[Rhymingmechanic]

I rented a Grand Prix for a long highway trip a few years ago. It had the information center you could scan through for temperatures and mileage, and I remember the trans being in the 180 to high 190 range. That was a V6 with about 18,000 miles, but I don't know the year.

30 degrees is a big jump. Maybe if you post your model and trans data, others can give their temps for comparison.

 

[PhillyJoe]

Never hear of trans fluid running 130-140 degrees except 6 blocks from start-up. Normal trans temp in this car is 180-210. Above 220-225 would be a concern. Dex VI is synthetic and this engine doesn't need a aux cooler, but many people do get nervous at 200 degree temps. I drive a 2007 Grand Prix with a supercharger.

 

[sciphi]

170 isn't out of the ordinary for a GM transmission. If you were saying it was >200 all the time, that's concerning.

If you're really concerned, take it back, ask what they did, then install an auxiliary cooler.

With a cooler, my Buick's 4T65 runs at 140-160 during the summer. The cooler is unhooked in the winter as the trans doesn't get above 140.

 

[SteveSRT8]

actually, due to typical GMC design, the trans fluid will usually be just slightly cooler than engine coolant temp. This is for the larger vehicles with side tank radiators found in the V8 RWD platforms.

With 205 thermostat our 6.0 gas powertrains pull a 9500 pound load at around 180 trans temp. Peaks of 190 have been observed.

 

[mechtech2]

That is a big jump up in temperatures. Fluid life will be 4 times LESS! [of those components that are heat degraded]

But actually, 170 could be very normal. I would not otherwise be concerned, except for the drastic sudden change.

 

[El_Schaf]

I do quite a bit of highway driving, and can say that the transmission temps are usually 110* to 120* above ambient temperature. On occasion, if I hit construction into the drive, the transmission will get much hotter due to stopping sometimes near 135* above ambient, but that only lasts until I get moving again and can cool the car down.

 

[dwendt44]

Dexron VI is a blend.

 

[El_Schaf]

Originally Posted By: dwendt44
Dexron VI is a blend.


Dexron VI comes in blend and full.

Valvoline makes a full synthetic version, super tech is, although I don't believe it expressly says on the bottle, a blend. I am not sure on the GM label.

I believe Sciphi and PhillyJoe have the most accurate temp range listed in their responses.

 

[pavelow]

170 is nothing to be worried about.

 

[ATS-V]

Originally Posted By: pavelow
170 is nothing to be worried about.

x2

once you start getting over 220 for extended periods of time the fluid starts to degrade faster.

 

[onion]

170 is comfortably cool for ANY atf.

 

[meep]

installed a gauge on my 01 T&C. sat at 140 until 45 minutes, then stayed 170-210 depending on traffic. I think that increase is fine.