My 2003 Chevy Silverado is saying low oil pressure and is down at 0psi and has a lot of grinding. once I start driving it for about 2minutes it finally kicks up to about 30psi and the grinding stops.

Its called Lucas Engine Oil Stabilizer like I said no promises but it is worth a try.

I know it worked on a vehicle I was working on the had a very load and constant tap after 45 minutes to an hour the tap was gone.

how many miles? prob could be just the oil pressure sensor?

This could be a false low due to a bad oil pressure sensor or a clogged screen at the sensor. Then again your engine may be worn out.