Tom, Since this is a "live" oil thread I couldn't resist a general oil theory question:
I've learned quite a bit from reading your previous responses on oil threads and I've noticed that you put a lot of stock in the additive package of the oil, while on the other hand the marketing for oils like RedLine and Motul push the fact that they use a Group V ester base that reduces the amount of necessary additives which they claim may "sheer" under certain conditions. Is this a legitimate argument for the extra expense of a group V oil?
One type of additive is a very large molecular weight component designed to provide the multigrade viscosity performance. These large molecules shrink in the cold, so they do not interfere as much with flow, and let cold oil behave "thin" and runny. At higher temperatures they expand, unfurl, and generally get in the way, so the oil behaves "thicker". These additives are viscosity modifiers or viscosity index improvers.
Because they are physically large, they can stretch or break. However, if one large spaghetti piece is cut in half, the thickening power of the two smaller pieces is not the same as the one long piece. Some VMs are more robust than others and resist this shear. Some formulations just put more smaller VMs in the oil so it shears less in service. Other VMs are designed differently, such as a star-fish shape rather than a long spaghetti. The star polymer can still provide thickening because the diameter is large, but the length in any one direction is not. So it is more shear-stable and less likely to shear.
People may argue that high speeds and high loads and high temperatures shear an oil more. I will remind you that a particular viscosity grade (pick SAE 30) is actually a range of 9.3 centiStokes to 12.5 cSt. So if the oil started at 12 cSt and shears to 11 cSt it is still an SAE 30. I would then argue that since the oil stayed in grade, the engine won't really know or care. These ranges were, after all, chosen for that reason - that within the range, an engine performed the same.
Higher "performance" base oils like synthetics have a naturally higher viscosity index. That means to make a 10W40 with cheap mineral oil you may need to add 10% VM, but to make a 10W40 synthetic you may only need 6%. In service the synthetic will shear less because there is less VM to shear! Esters are directionally better than PAO or Group III base oils, so I will give the benefit of the doubt to Motul and the ester blends that they shear the least.
The amount of VM in an oil is not exactly intuitive. A 10W30, 15W40, or 20W50 would not have as much as a 5W30 or 10W40. Synthetics will always have less than an equivalent mineral oil version.
With the science behind us I still would not base a purchase decision on shear. All API certified oils have test requirements to stay in grade. Any type of synthetic oil has less VM to start with, so will shear less. Your engine can't tell the difference of a 1 cSt change in viscosity. Performance oils would use a more shear stable VM anyway. Have you ever heard of an engine failure due to shear? (I haven't.)
Esters have a high natural viscosity index, high temperature capability, are polar and stick to metal surfaces, and some other technical benefits. These are more realistic performance enhancements than claiming better resistance to shear.