Just curious what everyone uses depending on big block small block or region of the U.S.? time of the year for you guys in midwest and up north.

10w 30 Valvoline VR1. Chicago SB, solid flat tappet

10w30 for me. I know some guys like 15w40 but that's too thick for me on cool fall days.

I run Brad Penn 5w-30 in my 340 in temps from 45-95 degrees.
I have tried 15w-40 but it was too thick and it made the lifters tick at WOT and on cold startup. Then I tried 10w-30 and the WOT lifter tick was gone but then I still had some minor lifter ticking at cold startup. So then I tried the 5w-30 and I have been running it ever since with no lifter ticking problems except for the at the very first startup after it has been sitting all Winter long.

The local engine shop suggested that the older engines will last longer by running Rotella T. I am running 15W40 where I live in Georgia in a 440 block used as a semi-regular driver.

I like to run 5w30 with plenty of zddp.
should be heavy enough if your bearing clearance is good and your oil temps aren't too high.