Two of the very most common viscosities found in contemporary car motors are 10w30 and 10w40. As the first area of the numbering shows that these two engine oils are basically the same, they differ in the second component. Theoretically, if one really wants to understand the variations between these two engine oil viscosities it is critical to gain an understanding of how the oil grading system works.
The Viscosity of Oil
Before we start deciphering the figures on these oil viscosity ratings, let us first establish a obvious understanding about the viscosity from the oil.