Question in regard to oil pressure gauge reading on 68 GTO. Seems the gauge is reading very high in any driving condition other than low speed in town driving. At highway speeds of around 55 to 60 mph (about 2800 to 3000 RPM) the gauge is pegged to the high side. Engine temperature is good, just below the mid point. What would your diagnosis be? I know nothing of the history of this engine, but suspect it is stock in every way, original to the car. Thanks in advance for any advice.