As anyone who's read Wayne's book or broken in a rebuilt engine knows, the first oil change following startup contains "millions of tiny flakes" of metallic particles caused by the engine's moving parts wearing in against one another.
I don't know for certain, but I would imagine that these particles originate at the cylinder walls, where the rings wear in against the cross-hatch on the cylinders, and the peaks on the cross-hatch wear down as the rings slide over them. Likewise, other bearing surfaces, such as the inside of the rod ends and rocker arms, probably contribute their share of particles.
On the inside of the case, at the parting line, squeezed-out 574 or other sealer can break off and fall into the case.
Some of this crud should fall into the sump below the level of the scavenge pickup, and is removed when the sump plate comes out. (owners of "modern" 1983- on engines have to rely on a drain plug). What gets picked up by the scavenge pump gets sent to the oil tank, where it runs through the filter before falling into the bottom of the tank, which also acts like a gravitational separator. But then it flows out of the tank into the pressure stage, and gets sent through the oil cooler if thermostat open, otherwise, into the main oil gallery feeding the bearings, and then through the cam oil lines to the valvetrain, where it falls into the oil return tubes and starts the trip all over again.
So here's the question: what damage is being done to the oil cooler, the main bearings, the camshafts and valvetrain, and other moving parts, during the break-in with the particulate being recycled?
Would it make any sense to replace the engine cooler with an oil filter, 906-style, with lines to an external oil cooler, during the break-in period? This would allow an additional filtration stage before the main bearings. In addition, much success has been reported with an oil cooler in the pressure circuit as opposed to in the scavenge circuit, probably due to the fact that there's less entrained air.
Has anyone actually done this? Or do the many filtration stages (pickup screen, spin-on-filter, oil tank) make this overkill?