Some folks like to i.e., blend some Mobil 1 15w-50 with the 10w-30 to increase the overall viscosity since the 10w-30 is on the lighter side of a 30w. Thinking about this, wouldn't you not end up with a i.e., a xx-40w but two distinct viscosities floating around in your oil system and not an average of the two? If so, I don't see where this is beneficial or even the desired result as wanting a higher 30 wt isn't the same as wanting *any* 50 weight. Maybe I'm thinking about this all wrong. Does anyone know? Your thoughts from a theoritical perspective?