Since synthetics perform better than conventionals in extreme cold and hot, have you proven your point? If you are trying to say that 80W-90 outperforms 75W-90 by using viscosity numbers at 40C for various lubes, I would say you have not proven anything.My point? I said it in the first post.
So I made a table in which it is visible that 75W-90 is not always identical or better with the specced 80W-90.
Also, the wear of gears, while pumpkin is warming up, or in cold ambient weather, might be higher than the one at operating temperatures, when dilation makes things tighter.
That certainly is true for engines in warm-up condition.
Also, for the text I bolded, are you referring to wear that potentially could happen due to conventional oil not flowing as well as a synthetic in cold temperatures?