Q: What is the difference between 0W-20, 5W-20, 5W-30, 10W-30, 10W-40, 20W-50 oils?
A: The difference in the oils is viscosity. Viscosity is defined as the resistance to flow. Oils that have two numbers in their rating are called multi-grade oils. Oils that have lower numbers are lighter (thinner) than oils that have higher numbers. Multi-grade oils are tested at various temperatures, allowing them to be used in a variety of climates and conditions. When the engine is cold the oil must be thin enough to get to all of the engine’s components, but when the engine warms up the oil must not be too thin as to enhance engine wear. For example, 5W-30 oil acts like SAE 5 when cold and SAE 30 when warm. Always refer to your owner’s manual for the correct viscosity rating for your vehicle.