I disagree that ester oil, or at least Nissan's formulation is more shear proof than other synthetics. Here is my uoa on Nissan Ester. Notice it sheared out of grade at 3k miles. I switched to Castrol Edge Titanium, we'll see how that looks.
Thing is the grade range is actually pretty wide. So there can be as much difference in viscosity between a given 20 and 30 weight as there is between two 30 weights, with one at the light end of 30 and the other at the heavy end. You can see from the manufacturer's info what the oil viscosity really is at the standard test temperature. A person could use one that is on the heavier end while still staying with the manufacturer's recommendation. I wouldn't stray too far from that, a light 10W30 maybe, but 15W50 and such? No way. You could probably also mix grades of an oil to come up with one that is heavier, yet still in spec. This is what I may end up doing if the Castrol shears out of grade. I've read that M1 High Mileage is at the heavy end.
BTW if your temps are normal I wouldn't go out of my way to go up multiple grades just because it is hot out. 220F is not hot for these oils, they do the viscosity test 210-212F in the first place.