The old pumps have their own oil charge (red cap in the back). They don't share common oil like the 617 and later engines do, so they need the oil changed from time to time.

Injector pop pressure AND spray pattern are both important. The pop pressure sets the timing, spray pattern is important for proper vaporization/combustion. If the pop pressures are off very far, it will affect the spray pattern and cause uneven power and a rough idle.