MC

In my 80SC, I am experiencing some rise in my oil temp gauge. The first year I had the car, the needle never moved "out of the box". It stayed right below the line. At first I thought I was low on oil, but the dipstick still reads above the fill line. Usually the druck press gauge and the rpms are about the same while driving. But, when this happens, the oil temp gauge goes up, the druck press starts to go down (doesn't match rpms), and there seems to be a power loss. It happens after about 20-30 minutes of driving, yet it doesn't happen all the time. I'll pull over to check the oil level but it is always ok.

Sometimes the oil temp will rise slightly out of the box yet stay there and not rise any further. Anyone want to take a stab at this mystery? Other than changing the oil and filter, any suggestions? Anyone else had this problem?