So, what do those oil numbers mean?

Motor oil serves several purposes in an automobile's engine, including heat dissipation and lubricating the engine to reduce friction and prevent wear and tear. So, what do the numbers about oil mean ?  Those numbers refer to viscosity, a fluid's resistance to flow. Thin fluids possess low viscosity because they flow easily, like water. Thick fluids have a high viscosity due to their slow flow, like  molasses. The Society of Automotive Engineers (SAE) establish standards, or specifications, for motor oil viscosity.

Let's look at a typical oil designation, such as 5w20.  The first number indicates the oils cold temperature characteristics. The lower the number, the colder the temperature at which the oil will flow and still protect.  The number after the 'w' is the high temperature characteristics, based on SAE specifications and standards. Since all motor oil thickens as it warms up, once the engine is warm and running the viscosity rating after the 'w' is important.  The warmer the ambient operating temperature is, the higher that number needs to be.

As an example, a car in Chicago would want a lower viscosity rating, say 5w20, than a car in Orlando, say a 5w30 or even 5w40.

So, can a 0w30 oil protect?  YES!  Remember,the first number means flow characteristics.  A 0w oil, if it meets SAE standards, will protect even in extreme cold temperatures.  AMSOIL Signature Series 0w30 is guaranteed to protect your engine in the most extreme conditions, and give you extended life between oil changes..