Chevrolet: 1996 Tahoe Oil Pressure, oil pressure gauge, 5w30 oil

Question
My wife has a 1996 Chevy Tahoe with a 5.7L V8. The engine has about 90,000 miles on it. I run Castrol 5W30 oil with Purolator premium filter in it. Recently she mentioned that the oil pressure gauge was bouncing around rather than the steady 50-60psi reading it has been showing. The gauge is really sporatic with a starting oil pressure of about 40 psi at cold idle, climbing to about 50 psi when you bring it up to 2000 RPM, but after it warms up it only reads about 30 psi at hot idle. The engine is quiet and smooth with plenty of power, but the oil pressure concerns me. I'm afraid I know the answer but I have to ask. Is it possible that it's the gauge or sending unit, or is it time for a rebuild?

Answer
Doug;
Hi I would not worry , if it is running good, I would get the 5w30 oil out and put in some 10w40 with a can of STP. it should bring it up good. it could be the sending unit or the gauge - but as long as you have oil psi.  it should be ok. but I would change that oil.   ok