Thanks for the info. I drove my sister'* car today since mine is still not fixed. I noticed that the lost in oil pressure is worst after the car has been driven for a while and the engine is good and hot. I notice sitting at a light the pressure would drop down to the upper part of the red line; which I am guessing is around 10 psi. The oil should increase in viscosity to 30 weight if this multi-weight oil actually does as it says. I would think the oil pressure would worst when the oil was at its thinnest. In fact, my sister'* son accidently installed 5w30 instead of the 10w30 the engine calls for. However, when the engine is first started and driven the oil pressure behaves better than when the engine is good and hot. That makes me believe that clearances are increasing in the pump after it reaches the max operating temperature of the engine, or that the fuel pressure relief valve is sticking after it gets hot. I still don't think the engine has proper pressure when first started, however, it gets worst when the engine reaches max operating temperature.

Then again, the strainer could be clogged as well and the oil is suppose to be at 30w under operating temperatures which could explain the lost of pressure with a hot engine versus the cold engine when the oil is at 5w. Maybe.

I don't think that you have a problem. Oil pressures are always higher when the engine is cold. When the engine oil is hot and thin the pressure is lower. The older buicks would have the oil light blink on and off at idle. This is considered normal. As long as you have pressure when you are over 2000 rpm then you are okay.