How to Choose Your Outboard Motor Oil: Viscosity

The viscosity is the most important spec to consider when purchasing outboard motor oil. Essentially, the viscosity is a measurement of how well the oil flows. As a rule of thumb, thick oils have a high viscosity, and vice-versa. If your oil’s viscosity is too low, it will lose strength at high temperatures, while if it is too high, the oil will not be able to pump to all of the necessary components of the engine.

The weight of the oil corresponds to the oil’s viscosity. Higher weights indicate greater viscosity in the oil. If there is a “W” next to the number, this signifies that the oil has been tested in cold temperatures and is approved for winter use. Tomorrow we will wrap up our discussion on viscosity and highlight multi-viscosity oils.