Breakdown of motor oil sales at fast lube shops in the U.S. by grade 2019

The 5W-30 motor oil is the most popular choice among drivers in the United States. In 2019, 5W-30 motor oil accounted for 34.2 percent of total sales. The number and letter combination of motor oil grades describes the viscosity of the product at different temperatures and the product choice is dependent on such factors as weather, performance level, and specific vehicle requirements. 5W stands for level 5 viscosity at low temperatures and winter (meaning the oil remains thin in colder weather and is suitable for sub-zero temperature use). The number following, in this case 30, indicates the thickness of the oil at normal operating temperature. 5W-30 serves an outside temperature range from -35 degrees Celsius to 30 degrees Celsius.