Trans temp is to hot

[Trenton oliver]

So out of nowhere today i decided to look at my trans temp and it was at 230 degrees and went up to 240 then cooled down. I was wondering before i take it to a shop to get anything done. What could be causing this it’s still shifting smooth has butter with no issues. 
 

[CamGTP]

I mean more information is helpful.

 

What truck, what engine, what transmission. Temp outside, pulling a load or just driving normally?

 

All stock truck? Any history of fluid changes or updated parts used for the thermostat?

[Trenton oliver]

2017 gmc sierra 1500 5.3 6 speed and 75 and just driving normally trucks all stock put a new transmission in last may. When new transmission went I put a new updated thermostat in 

[rlcole321]

Why did the last trans fail?, did they flush out the Trans cooler/condenser good? if it was a Torque Converter failure and cooler was not flushed properly, or the new 152 degree trans stat is not working right, that's where I would start.