This was non-detergent motor oil. When detergent motor oil was introduced there were stories about how detergent oil would damage engines that had never been run on it. Apparently all the sludge was helpful in sealing leaks and keeping oil pressure high.
So is this oil test verifying what we have also been told? That most engine wear occurs on initial cold start up, possibly when the oil did not flow very well for the first few seconds. Could this be why most older cars were smoking (or using oil) at 100,000 miles ?