Valvoline VR-1 vs. Lucas Hot Rod oil
Will oil pressure help understand what viscosity it likes best?
Yes.
The pressure on the gage is from the pump, after the relief valve.
We can use that as a clue as to how much volume is making it through the system.
An oil that is too heavy will have higher pressure at idle and max out at lower rpm.
An oil that is too light for the clearances will have lower pressure at all rpms (at operating temperature).
Oil pressure when at operating temperature should be 10 to 20 psi at idle and go up with rpm.
It should increase until at least 3000 rpm, preferably higher.
Oil temperature is of key importance. An oil that is at 160 or 180*F for a run at the drag strip will have lower viscosity when its at 220*F during a long haul up the Rockies.