Here's a post copied from the BGM site of maybe something to ponder:"Does it have a Delco 50DN hanging anywhere with a #16 oil return directly to the pan ? The amount of copper , lead , bearings , and most anything else can directly make it to the oil pan .don’t be so fast to yank the head off a perfect running 60 series."@Richard Your mention of something precipitating out of solution to form those nodules caught my attention but is above my carpentry skills.