08silverbullet

What altitude are you at? In Texas Here at sea level and on a hot day like today I have seen mine climb into the 160-180 mark is also around 100 here

stmar

A mile high where I live and higher most of the time. Probably anything under 200 is normal on a hot day when the tranny is working hard. Just cruising in overdrive it is in the 150 - 180 range. When I am going downhill for a time it backs down to the 150s and engine drops to mid 190s. Having a cooler should minimize any risk of overheating. What thermostat do you run in your 4.6? Mine opens at 206, then run temps are the 190s.

08silverbullet

Mine is still factory truck just hit 46,000 miles yesterday

homer

Also not sure if this matters (not sure what the Mercon V is - I thought it was at least semi-synthetic but maybe it's full too...?) but I'm running full-synthetic trans fluid. I *think* it's run cooler since but I didn't pay as much attention prior to that.