Engine oil viscosity grades explained

Engine oil viscosity grades explain how easily oil flows at different temperatures and are defined by standards such as SAE (Society of Automotive Engineers). A multi-grade oil like SAE 15W-40 or 5W-30 uses two numbers: the first number with the “W” (winter) indicates how well the oil flows during cold starts, while the second number shows the oil’s thickness at normal engine operating temperatures. Lower “W” numbers mean better cold-start protection, reducing initial wear, whereas higher second numbers provide stronger lubrication under high heat and load. Choosing the correct viscosity grade ensures optimal oil circulation, effective engine protection, improved fuel efficiency, and reduced wear across varying driving and climate conditions.