What does the 'W' stand for in engine oil designations such as 10W-30?

What does the 'W' stand for in engine oil designations such as 10W-30?

• A. Wear
• B. Winter
• C. Wide
• D. Water

Answer: (B)

Winter is what the W denotes in oil grades like 10W-30. The oil’s labeling uses two numbers with a W in between to show how it behaves in cold and hot conditions. The first number before the W indicates cold-start viscosity—the smaller that number, the easier the oil flows when the engine is cold, which helps protect the engine during startup in winter. The second number after the dash indicates viscosity at engine operating temperature (hot). So 10W-30 means the oil behaves like a 10-weight oil in cold weather and like a 30-weight oil when hot. The W is not Wear, Wide, or Water.

Winter is what the W denotes in oil grades like 10W-30. The oil’s labeling uses two numbers with a W in between to show how it behaves in cold and hot conditions. The first number before the W indicates cold-start viscosity—the smaller that number, the easier the oil flows when the engine is cold, which helps protect the engine during startup in winter. The second number after the dash indicates viscosity at engine operating temperature (hot). So 10W-30 means the oil behaves like a 10-weight oil in cold weather and like a 30-weight oil when hot. The W is not Wear, Wide, or Water.