At a guess six months ago, it was changed, thermostat probably never, why do you think it boils so quickly and consumes the water when caught in traffic, but when moving all ok, and water fluid ok after cooled?
I was thinking maybe a head gasket?
How do the fans operate on a trans am 1987 GTA?
One fan comes on at 220 f, and the other does not operate.
Some forums say the other only operates with the air conditioner; others say earlier models only did this.
The water boils, car overheats quickly stuck in traffic; if the other fan was...