Is 10w30 an Obsolete Viscosity?

When it comes to synthetic oils, my belief is that 10w30 is now an obsolete viscosity. Why you ask? Because when given the choice between running a 5w30 or a 10w30, the 5w30 can do all the same things as the 10w30, but with the added benefit of flowing better on initial startup. So overall engine wear will be less. When it comes to conventional oils, a lot of people choose 10w30 because it has less viscosity index improvers in it, therefore it won't thin out as easily. But when it comes to synthetic oils, they use little to no viscosity index improvers in 5w30, therefore it will retain it's viscosity much better.