I had my truck out earlier, just turned 198k on it. 2001 Sierra 2500HD with the original early style Gen III LQ4 6.0l.
A little over 6 years ago I did the Oil Pan gasket and while I was there I pulled down the pickup tube and installed the red Oring. It picked up 10psi+ at idle, used to hang around 40psi now it's 50-55psi hot. The Lifters don't make noise anymore. LQ4 has a factory high volume oil pump and it's Gen III so no pressure relief in the Pan, but that Oring is a pretty big deal. Any of you who get in that deep it's not a bad idea to replace it.
A little over 6 years ago I did the Oil Pan gasket and while I was there I pulled down the pickup tube and installed the red Oring. It picked up 10psi+ at idle, used to hang around 40psi now it's 50-55psi hot. The Lifters don't make noise anymore. LQ4 has a factory high volume oil pump and it's Gen III so no pressure relief in the Pan, but that Oring is a pretty big deal. Any of you who get in that deep it's not a bad idea to replace it.