Originally Posted by ChrisSlicks

Correct. A 0W weight is a thinner viscosity than a 5W or a 10W and hence even at warm temperatures will be better for your engine at start up. But as I said before the light weight oils are the ones that break down first at high temperatures, so if you are canyon carving and your oil temp is hitting 260+ on a regular basis then it might not be the right choice for you even though it might be the right choice for a commuter car.