You should be running 10w30 all the time. Los Angeles doesn't get very cold or very hot, as compared to other areas in the state. I run 10w30 in areas that get down below freezing and into the triple digits most of the summer.
When you change your oil, is there any shiny specs? It sounds like your bearing clearances are a little wide, or you may need a new oil pump. I bought a 292 with 155k on it, and it has 30psi while cranking. I haven't ran the engine yet, still getting parts to finish it, but you should have at least 30 psi at idle on your engine.
It might be worth the effort to drop the pan and check things out on the bottom end.
Heck, my 4.0 in my Jeep Cherokee with 207k on it idles at 30 psi and 60 psi above 1,000 rpm
Edit: I was wrong, the 4.0 idles at 60 psi when cold, and will drop to 30 psi when hot, and that is using 10w30.
Last edited by DoubleDingo; 04/23/21 08:20 PM.