1999 Chevy Suburban (1500) (2wd) 5.7 V-8 Oil Pressure guage show high (3/4 deflection) upon start up and remains high for the first 5 minutes of driving. Additionally the engine knocks during this time. After the first 5 minutes everything returns to normal. Any suggestions?

 

How many miles on the Suburban?
What viscosity of oil are you using?
How long since your last oil change?
How often do you change the oil?

Whan you say that engine "knocks" does it sound like a rod knock or more like a ticking?
How loud, can you hear it inside the cab with the windows up?

 

Suburban has 125,000 miles
Last oil change within the last 5000 miles, change every 3-5000 miles
Castro 5W-30 is the Oil I have always used.

The noise is more like a ticking which can easily be heard in the Cab with the windows up.

Local parts store managers thinks it's most likely "Lubrication Slop" built into the engine...
Have owned the vehicle for 7 years (80,000 miles) and this is the first time it's every done this
so "Lubrication Slop" is a little hard to believe.