ken56 wrote:
So then how hot is too hot? My tranny in normal driving/towing runs just under 200 degrees, like 196/198 and has since it was new. I take that as the normal operating temp. Going up some hills it has been up to 210, not a big jump up off of normal. I have a '14 Silverado with the 6 speed electronic trans.
For your truck 200 is normal. Your truck has a normal operating range of 160 - 200 degrees. It's expected that you will exceed that while towing in hot weather. If you're towing often and exceeding the normal operating range regularly then you may want to follow your Severe maintenance schedule.
Transmission fluid will work fine even at 300 degrees, but the life expectancy of the fluid is severely reduced. Running at 220 degrees for an extended time is normally the mark where you have to start getting worried. At 220 the fluid begins to break down and varnish begins to form. 220-250 is fine for a few miles like when you're pulling up a grade. However, if you get into this range it's best to slowdown or pull over to get the temps into a more reasonable range.
