The point of extended oil changes were to be a cost effective way to protect engines that required large usage of oil. That is the sole purpose where UOA's came into play to confirm that there was added life in the oil. There is no doubt that oils of today are many times superior than than those of yesteryear and is seen in the manufacturers increased required intervals. Scientific data. Motorist like yourself are trying to extrapolate without doing the research. A better way may be just to change the filter halfway in between and confirm that your oils life can take more usage.
Keep us posted as to how your luck runs.
Keep us posted as to how your luck runs.