i actually put this to the test after pulling out some very dark sludgy looking oil out of my hp oil res once, after reading that it circulates. I put some uv dye directly into the oil fill tube let the truck run a bit then stuck a small screwdriver into the hp oil rez to find that there was UV...
Installed a crossover with my coolant filter and noticed nothing, in fact, I just got done replacing the #6 and #8 supposed LL long lead injector, which the crossover is supposed to supply more oil to. I feel like the amount of oil that will fit in that confined area is finite and since you cant...