Northwest Petroleum - Engine Oil Viscosity Grades Explained | The number before the W indicates the oil's viscosity at low temperatures. The lower this number, the easier the engine starts at a
Filter House - "KNOW ABOUT OIL GRADE" What does 10w40 mean? The purpose for which it is intended (i.e. Motor oil, Gear oil etc). The viscosity (i.e. 10w40, 5w30 etc for Motor
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