i took some really cool classes in college, and if i remember correctly, the winter number is not a viscosity, but a behavior. it BEHAVES like a 10 weight oil. it equals the lubricating qualities of a 10 weight at the specified temperatures. it was exactly one million years ago tomorrow, so i could be wrong.
All multi grade oils base oil starts as the winter grade.
That is, a 5w30 is a 5 grade oil with viscosity index improvers to make it function like a 30.
Just because you think it won't make it true. Horsepower is KING. To dispute this is stupid. C. Alston
