Hi, 75 TR6 Mileage probably 100k+ US miles. New 20-50 oil, pressure hot and cold about 65psi gauge, running fast or idle. After about 40 miles the pressure dropped to 55psi at 2000rpm but 25psi idle. Is this likely to be a problem with the pressure control valve or something else? Engine runs smoothly oil pressure normal 65psi next day. I have only had the car for a couple of weeks. Cheers, Michael