Oil??

Maybe the BITOG additive report is a bit flawed but I think the test is applicable because crankshaft windage and gears inside an engine can cause air entrainment.

Personally, I would think that an engine oil is already equipped with all of the additives it requires and I don't think I can do a better job of formulating an additive package than the manufacturers. If it works for you, then I think you should continue using it but I also think your vehicles would be better protected with 100% HDEO of whatever brand you prefer (see Corvair Oil Recommendation - Recommendation 33 & 34, p 20 & 21). My 2¢.

Anyway, the original question was about viscosity and not about oil brands or additives.