The winter grade number is only meaningful if you are running below 32* F or colder. A 5w30 or a 0w30 means nothing unless it's freezing or colder. It's still a 30 grade oil, which as we know, viscosity grades are a mile wide.
Just because you think it won't make it true. Horsepower is KING. To dispute this is stupid. C. Alston
