my buddy has an 01 c5. bone stock. when you start it up in the morning, it reads zero oil pressure until his revs it. then it goes to 40. doesnt knock, didnt see any metal in the oil. just put a new oil pressure sensor in an it didnt help.

anyone got any ideas?

 

How many miles ???? The oil pump could have some gunk in the by-pass valve
causing it to act up. A new LS6 pump is like $150 from TSP

 

right at 100k

 

I would replace that pump,, its cheaper than what may happen if its on the way out.