Since i only drive mine at 60* +, i use Valvoline 30W.
Tried Pennsoil a couple times, but pressure would drop about 5-10lbs after only 1000 miles.
Switch back to V-30, and it wouldnt drop for 3000 miles.

This year will see 6000+ rpm's, so i'm gon'a use Valvoline 20-50 racing.
After helping guys at the track last 2 seasons, this seems to be the oil of choice.
Can tell you for sure it made a big diff on brg life on Ray Cox's 7000+ rpm engine.
He used Pennsoil 20-50 racing before. That crap is like motor honey.
Gained a tenth and 1.5 mph with no over changes.
He'l never admit it cause it was my idea.