Engine oil viscosity grades, defined by the SAE (Society of Automotive Engineers), describe the oil’s thickness and flow characteristics at different temperatures. The number before the “W” (e.g., 5W-30) indicates how well the oil flows in cold conditions — lower numbers mean better cold-start performance. The number after the “W” reflects the oil’s thickness at high operating tempera... https://millenniumgroup.ae/engine-oil-viscosity-grades-explained-a-complete-guide/