Temperature guage on 1998 BMW 528i

I am in florida, the outside temperature is 92 degree F. the problem is that when I stop at the red night or waiting for about five minutes with the air-condition on only, the temperature gauge is rising higher, and going toward red zone, but when I increase the speed and not waiting or slowing down idling around 700 rpm, the temperature is normal all the time, so that I know you mention that we should use bmw coolant becasue of some high tech ingredient which i did not it yet, what do think of any issue related to this matter, thank you

Asked by for the 1998 BMW 528i
I will forward you an article I wrote for Repairpal about cooling system problems.I will send it to the email address you posted this question from.
One thing comes to mind with some European cars around this time (Jaguar V8, some VW and BMW's) the water pump impellers were made of plastic and either slipped on the water pump spindle or fell off altogether causing the same conditions you mention . At speed rush air through the radiator keeps the engine cool, at idle at a stop sign there is no air rushing through the radiator and the water pump and fan must be working efficiently. I will forward the article now.
can you help me of how to change the auxiliar AC fan? step by step?
1 more answer
BULL#$@% ! Just have it flushed throughly & put a good universal coolant in it. I don't believe they have nano technologly in coolant yet.