What Does 15W-40 Mean: The designation 15W-40 is an SAE viscosity grade for engine oil, where 15W (W stands for winter) indicates how easily the oil flows at low temperatures to support smooth cold starts, and 40 shows the oil’s viscosity at normal engine operating temperatures, ensuring adequate thickness and protection under heat. This multigrade oil is designed to perform reliably ... https://millenniumgroup.ae/what-does-15w40-mean/