In this month Event Topic we are going to go over how to translate what the numbers & letters mean on a jug of oil. In any typical oil brand you have two sets of numbers, a dash and a letter. Keep in mind oil is defined totally on viscosity so both sets of numbers will be based on this fact. What is Viscosity. Viscosity is the resistance of liquid to flow. So water has a lesser viscosity than molasses because it flows easier in travel.  Our example will be 10W-40. We will start with the definition of the letter "W" and what it stands for. So the letter "W" stands for Winter. Not weight or watts or whys... nothing more, nothing less. So the number right before the "W" states that at the coldest temperature (hence the winter part)  the oil was engineered at will have a viscosity of 10. At the complete opposite side the higher number indicates the less viscosity the oil will have at high temperature. Once again it depends on what that company engineered the oil temperatures to be. Different brands will have different levels oil operating temperatures, which will cause their viscosity.