For the truck in my sig what is a safe operating temp range for the (stock) auto trans? The hottest I've seen it is 150, that's also when it's been the warmest outside, which is 52 F (i've only had the truck for two months), that was running empty, and around town, and trying to go real easy with my right foot. I should have a built tranny in the spring (if all goes well)...just trying to make sure the stock trans makes it that far! I am using a Edge CTS with trans pan temp sensor to read this. It screws into the threaded hole (that had a plug in it), on the side of the trans...above the trans pan on passengers side of truck).

 

150 is a great operating temperature. 200 driving around town should be expected, especially without the heat exchanger. 230 is Max you would want to see.