Which SAE multigrade oil is likely recommended for year-round use in North America?

The correct choice, which suggests 5W-30 multi-grade oil, is favored for year-round use in North America primarily due to its versatility across a wide range of temperatures. The "5W" indicates that the oil flows like a 5-weight oil in colder temperatures, which allows for easier starting and better engine protection during cold weather. The "30" denotes its viscosity at higher temperatures, providing adequate protection and lubrication when the engine is running hot.

This oil provides a balance that makes it suitable for both cold starts in winter and the higher temperatures experienced in summer. It maintains performance and efficiency throughout the year by adapting its viscosity appropriately based on temperature, which is a critical factor in areas with significant seasonal temperature variations.

In comparison, the other options either have a higher cold viscosity rating, which may hinder cold weather performance, or are less adaptable to both extremes of temperature, making them less suitable for year-round use. For example, 15W-40 would be better suited for warmer climates but may not flow as well in very cold conditions, while both 20W-20 and 20W-50 are too thick at low temperatures, leading to poor cold start conditions. Thus, 5W-30 stands out as the