I recently switched to Rotella T (15w/40) from VR (20w/50) in my 427. With the latter, my oil pressures were always very high, minimum 40 psi at hot idle and about 80 psi with even low revs. The lower viscosity Rotella dropped the pressures about 10 psi on each end, still not low and in a healthy range.
Naumoff and I have been discussing the virtues of a little lower viscosity for cold start-ups. I suppose if I were racing or running the car hard all the time, VR might be preferable.
In addition, there have been a number of write-ups and discussions on the desirability of zinc in oils for solid, flat tappet cams, which I have. Std. oils have been losing zinc, and Rotella still has a good zinc content.
Clay
1998 Unique #9299,
427FE side oiler (452.1-stroker)
Top-loader (close), 3.31 rear
Annapolis, MD