Whenever I sell a job that has anything to do with the cooling system, a new cap goes on it.

So I just assumed the radiator cap was new or had been tested by the shop you took the car to.

I say...everyone that does not know their cap is good, go buy one today !

And your original complaint was that the temp gauge was fluctuating, so that will be caused by low coolant in the engine. Keep an eye on it.

Thanks for the heads up. I'm going to flush the coolant system soon. Its prob. hitting bubbles and dropping i'm guessing.