Viscosity refers to the weight and thickness of a motor oil. Motor oil gets thicker when it’s cold and thinner when it heats up.
While some racers see the “0W” and think this oil would be too light, in fact Mobil 1 Racing 0W-30 and 0W-50 are the same weight at operating temperatures as other SAE 30 and 50 grade oils.
Mobil 1 Racing oils are designed to help protect an engine at lower temperature as well as providing excellent protection and durability at operating or race temperatures. The wider viscosity range is designed give more efficiency which can potentially result in better fuel economy and increased horsepower.