I have a 96C Chevy stepside Cheyenne show truck. Obviously 5.7 engine, via title.
I use 10w30 PUP, or PPHM, basically swap between each change, every 5k miles, or 6months.
At cold idle/start, with it being 80-100 degrees outside, I get about 75psi. Once warmed up about 55-60 at 55-75mph. And...