More on the topic of choosing motor oil viscosity grades.
Even though the UOAs shown in the links below are from a 2004 Ford 6.0 Powerstroke diesel rather than a gasoline engine, isn’t it interesting how the 30-grade motor oils show as good as or better wear numbers than the 40-grade motor oils used.
30-grade motor oils are tough to beat even in the demanding conditions of a diesel engine.
I wonder if this person had slightly better fuel economy with the 30-grade oil?
Click on thumbnail to view UOA report.