Question about oil viscosity 5w40 oil?

My friend says that 5w40 is too thin to use in a warm climate like hawaii, and that 10w40 would be better.





I was under the impression that the first number was the viscosity when cold, and doesn't matter once the engine is warmed up. Can someone explain?Question about oil viscosity 5w40 oil?
You are correct...your friend is wrong.





http://en.wikipedia.org/wiki/Viscosity_i鈥?/a>Question about oil viscosity 5w40 oil?
Just look at these sources to find your answer.

blemishes