Originally Posted by marquette97
the onlt time the pressure seems to drop is after i am been driving 70-75 mph on the expressway for more like an hour or more. then after the car sits for a long time off, it goes back to normal.
Sounds like your oil is just thinning out from the heat of heavy running. This is most often noticeable when coming to a stop at the bottom of a freeway exit ramp. The problem in that case is heat soak. The engine cooling system stabilizes on the highway with lots of air rushing through the radiator. Then you come to a stop. The water pump is turning much more slowly, there is no air flowing through the rad, and the cooling system cannot deal with the residual engine heat, so the oil thins and you observe the pressure drop.
Also, what viscosity oil are you using? With the mileage on your engine, you might benefit from running a heavier weight oil. I run 15w40 in my '95 year round with no winter starting problems.