This article discusses oil viscosity and what does it mean? It explains how viscosity is the measure of internal friction or its resistance to flow. Thin and light is low viscosity and thick and heavy is high viscosity. It also explains why viscosity is the most important part of a lubricant and how well it protects your vehicle. Different vehicles require different viscosity oil and the ability to resist thickening.
Amsoil Synthetic Motor Oils resist thickening under extreme heat and will flow in sub-zero temperatures when conventional oils will not. Too low viscosity can cause increased metal-to-metal contact and wear.