Amazingly enough, the trouble was a freeze plug on the back of the head that popped out. The '
oil' must have been some sort of sludge in the cooling system (wetting agent?). Replaced the freeze plug, refilled the cooling system and all is good, at least for now. I let it run for about a half hour then took it for a ten mile drive with no problems. I initially considered freeze plug until I saw the '
oil' and another person said steam came from the exhaust. In any case, I hope this is the end of it.