I recently added an oil pressure gauge from a turbo 240 to my non-turbo 1980 245, swapping out the sender from the same car. When I had it installed and working, for several weeks the gauge would read between 4.5-5 bars, while driving at speed, idling, and even after the engine had turned off. I know it wasn't pegging out, and the gauge would move small amounts while driving, leading me to believe it wasn't stuck or broken. But recently, during a long road trip, I noticed that now while driving, at speed it reads about 3.7-4, when idling 3-4, and when I turn the engine off it reads a 1-2. Although the later conditions seem more normal for an oil pressure reading, I'm still nervous because it did change so drastically from the begining. Can anyone tell me what a normal reading is? Should I be worried?

Jason