Originally Posted by DVPGSR

A higher weight oil will be thicker than a lower weight oil. If you live in a southern climate where the weather is hotter having a higher weight oil in your car will not break down as much as a lighter weight oil. Conversely, in a northern, colder climate a lower weight oil is not as thick and will be better for an engine on a cold, winter day. It all breaks down to the viscosity level of the oil.