2004 4l80e hot trans on hills

I would never flush a transmission, that washes all of the junk to places it wouldn't be otherwise, probably blocking most of the cooler; just drain and refill,change filter, a couple of times if need be.. Mine runs around 150 normal and 180-190 towing 7000# camper.

akcooper, you don't want it to run too cool, ideal is around 180 I think, too cool and moisture does not evaporate in transmission