As a matter of fact the temperature gauge is irrelevant since E38, E39, E45 and E53 models. It will stay in the blue when engine is cold, move to the middle at 120F or so and start moving to the red over 240F. Once it starts to move to the left the engine is toast. This is how I overheated my first 528i and this is how millions of owners overheated their modern BMWs. In my E30 the needle will move visually with every 4-5 degree change of the coolant temp and I can figure out early if there is a problem of some kind. The only modern BMW with a real gauge is the E46 M3 which acts similar to the old school ones.

I've had more than a dozen BMW's and my temp gage was an early indicator of a coolant leak or stuck thermostat. I cannot imagine that once the needle starts to move the engine is "toast"? "Millions" of owners? Not trying to be confrontational but thinking a temperature gage is irrelevant is a bit much. It is interesting to note that the gage was returned on the 2014 F15 model X5.

The only tell tale sign for a coolant leak on, let's say E39, would be a coolant level warning, if the car is equipped with the sensor. I have personally done 15-20 M52TU/M54 head jobs, how many do you think around the world have been overheated? Every second or third of these engines has been overheated.

Where would I find the free online manual?