Thanks for the heads up Doug, but my question wasn't answered.
Today's oils are far superior to what was available 5 years ago, let alone 40 years ago.
Today's VII/VM's are far superior to what multi-weights were blended with back then too. If its simply a VII/VM issue, then I'm not worried. If its something else, I haven't seen it.
I haven't seen an issue with non-SAE40 in the gensets, pole/well drills, pumps, and trucks that were topped off regularly and filled with 15w40 in long term use. I've also seen some regularly topped off with 20w50 and 10w40, because that was what was available at the local nearest store. Any oil is better than none and there were no ill effects. Not every fleet or garage keeps barrels of every oil weight out there so I'd guess that the mis-oiled engines are more than what is spoken about on the web.
I understand the consumption issue and its not a concern.
There are plenty of >3.7 HTHS oils out there. SAEJ300 for a 15w40 20w40 25w40 and straight-40 requires it. The 0w40, 5w40, 10w40 requires 2.9 HTHS which probably would be sheared and consumed excessively. Some are >3.7 too if you hunt down and read the datasheets. And, the winter oil, per J300, 30wt HDEO requires a 2.9 HTHS. Makes you want to think that unwarranted 'fear' of 'nothing' is the only reason to stick with the SAE40.
I think that the shear stable DexronVI and ATF+4(over a decade ago), along with the performance seen from current oils, shows that we can make an oil with the VII/VM's work fine in ANY application.
I wonder where brightstock/slackwax would be on the chart here(maybe too far to the left and off the chart):
http://www.lubrizol.com/ViscosityModifiers/Asteric/default.html