So I've been looking over the old posts and still
am trying to see what guys are running for oil.

Have a fairly new 340 motor and need to choose an
oil. Tried 10-40 but my pressures are kind of high.
Running 80psi cold and 60 hot at idle to 1800 rpm.

Was thinking about changing to 10-30 to help bring the pressure down a little. Don't plan on racing this much just some street fun and I live in the north lands where it rarely reaches 90 degrees.

Looks like 10-30 was a suggested stock weight.

Yes I plan on adding ZDDP to the oil.