Temp gauge = idiot light?
 

Guys,
Has anyone seen their needle move after warm-up? Mine stays in the exact same spot after warm up, even after running subsequent WOT blasts through the gears.

I know from some cars I have had in the past, the needle could basically be read as an idiot light. If it was to the left of center, the car wasn't full warmed up. If it was to the right of center, it was already overheated (too late).

Is that the case with the Mustang too?

I have seen mine move a little bit well after warm up and hard driving. There is a normal operating range for temperatures but they are not indicated on the temperature gauge. I'm a pilot and I can tell you that in reciprocating engine light aircraft we have color coded bars along the oil temperature gauge as well as a published normal operating range temperatures as well as minimum and maximum figures. We adjust the fuel manually to keep the engine cool and efficient as well unlike a car. In a way it is an idiot gauge in our cars because of the way it's displayed without exact temperature readings. If the needle is to the left it's cold, if it's roughly in middle area it's normal, and if it's in the upper area it's hot. If it moves far to the right you'd definitely be getting an overheating condition.

It's done this way to avoid people bringing the car in for service cause "my gauge started moving more when I drove up in the mountains". Basically the "gauge" is in the normal range (vertical) from about 160 to probably 210-220, above there it starts to move toward the warm range. By 250 it basically pegs out, and most Mustangs will go into limp-home mode, cutting timing, limiting revs, etc.
If you get an aeroforce gauge, or a true temp gauge, you can watch the temps and see what has been programmed into the idiot gauge.

With my aeroforce ones I've seen 207 the highest when wot. Usually it sits at 190

My 4.6L sits around 190-195 around town, but on track have pushed 240 when bouncing off the rev limiter for a bit.