Transmission heating up ?

[David C]

Hi, while driving through the Adirondack mountains on my way to NYC and then back from Boston (Montreal-NYC, NYC-Boston, Boston-Montreal), I've noticed a lot of heat build-up by the transmission shift lever, mainly on the top of the lighted transmission position indicators (P-R-N-D-3-2-L), on both side of the floor center console (between front seats) near the shift lever and on the flat storage surface between the shift lever and the center dash. I don't know if my car ('07 A/T 3dr LB) has a transmission fluid cooler module or if this is normal and non-hamrful to the car, but I'm concerned about this being a sign of needed maintenance.

I was driving non-stop highway for hours, up and down hills, usually about 120-140km/h, so 3 000 to 3 500 RPM, with a quite heavy cargo weight and one passenger. After noticing the heat (about halfway through), I then did the remaining 300km staying below 3 000rpm, but even so the heat would still be moderate. On the way back, no passenger and lighter cargo (about 300lbs lighter overall), but still on mountain terrain highway, driving below 3000rpm would still produce moderate heat, but then when I got annoyed of driving slow and stepped it up to 3 500rpm (130km/h) up and down the mountains, the transmission and overall engine heat would actually reduce to minimal. Then when I got back driving 3000rpm (110km/h) and below, heat came back. I don't know if the cooler ambiant temperature and added air flow from driving faster and mostly downhill when I was doing 3500rpm in the mountains was enough to cool everything down or if the car is actually having issues managing the heat/cooling of the transmission at times, but I'd like to learn about what is going on and if anything should be done. I am due for an engine oil change (about 12 000km since last oil change), but I don't know if that plays with the transmission and if I should also change the transmission fluid ? Last time I did a check (few weeks ago), all fluids levels and color where good using the dipsticks. I've owned the car since january this year and I don't know the full service history, despite everything being in very good condition for a decade old car.

Thanks for reading