I have a 1990 acura integra in which the rad was recently replaced. I have noticed that the coolant gauge tends to stay on the low end, and drops off the scale if the heater is turned on (I'm in Massachusetts). I talked to the mechanic who installed the rad, and he maintains that it is simply a bad sensor, and that the reading has no bearing on how the engine is working. I'm a bit technically challenged, so I was looking for some informed 2nd opinions. Anyone?