The spec sheets available for pretty much every I'll ever use contain the viscosity #s that are used to find a "heavy" 30 or a "light" 40. That's why I posted those charts previously to make it easier for people to see things like this.
Oh, I haven't seen any pattern when checking the #s that indicates the "better" oils come in at the high end of their advertised weight. The brand doesn't matter; they can be all over the viscosity range for a given weight.
Exactly. The manufacturers have a wide field to work with as far as viscosity is concerned.
And your correct, most manufacturers post their oil specs on a web page. I'd rather call them
