Tex, thank you for that thread. A link to it is here:
V12 oil system flow and information
Seems that some of that information helps answer/inform a current thread about the type of oil to use in XJS V12s, and initial oil heating on startup.
Going back to putting pressure on the outlet of the oil pump versus the pump creating the pressure, if oil is taken from the sump for circulation purposes to an external oil pump, then injected under pressure between the pump and the filter, that pressure would still be on the outlet side of the internal oil pump, which may not be good for the internal pump.
I would hate to potentially damage the internal oil pump and then have to replace that when replacement is not currently needed.
I’m still questioning if that would damage the oil pump or not. Hopefully not. And hopefully someone knows the definitive answer to that question.