177K miles. I've had it for a couple years - has done this the whole time:

Engine temp changes frequently and irregularly. At initial warmup temp comes up to the dot in the middle of the gage. Shortly therafter (5-15 minutes), both in traffic and on the open road, gage rises rather quickly to w/in 1/8"=3/16" of the red zone, stays there for a short time, then drops back down to just below the dot. This cycle repeats irregularly. The higher the ambient temp outside, the closer to the red zone the temp gets. After being on the road for a few hours, the longer the gage stays at the high temp before dropping to mid-range, and remains at mid-range for a shorter time before again going up.

I originally thought that there is an incorrect thermostat in the car and/or it is sticking, but I have been told that there could be something called a temperature compensator board causing the problem. What is a temperature compensator board, how does it function and where do I find it and check it out? Is the coolant temperature actually wandering or is it just the indication?

Thanks.