When driving along with the car at normal operating temperature and outside temp at say 20 deg C you can hear the radiator fan droning away at up to 70kph in 3rd gear auto trans (not 4th). When the car is cold, after an initial roar, the fan is quiet as a mouse. The fan clutch looks like it might be only a year old so it is in good condition, just it seems to start to engage at an unnecessarily low temperature.

Could some of you 5 litre people give me an idea at what rpm the fan starts to disengage on you car? Slowly slowly bring the revs up and there will be a point where the fan slows right down and shuts up.