These are SAE (Society of Automotive Engineers) viscosity grades that class 4-stroke engine oils in relation to their hot and cold viscosity characteristics. There are 2 parts to a “Multigrade” viscosity product:

  • A cold grade, the “0W” or “5W” in the above examples. The “W” stands for “Winter”. The numbers go from 0 to 25 and give an indication of the viscosity at cold temperatures. The 0W will have the lowest viscosity and the 25W will have the highest viscosity at cold temperatures.
  • A hot grade, also called summer grade, the “40” or “30” in the above examples. The numbers go from 20 to 60 and give an indication of the viscosity under normal (hot) operating conditions. The 20 will have the lowest viscosity and the 60 will have the highest viscosity under normal operating conditions.

You should refer to the OEM's exact recommendations when choosing your engine lubricant.