Multi-viscosity oils should be used in:

Multi-viscosity oils are designed to provide effective lubrication across a range of temperatures, making them suitable for engines that experience varying operating conditions. In the case of two-stroke engines, which typically run at high RPMs and may operate in different temperature environments, multi-viscosity oils help maintain performance and protection throughout their operating range.

Similarly, in automobiles, multi-viscosity oils are commonly used as they need to perform well in both cold startup conditions and high-temperature scenarios during operation. This versatility allows the oil to flow easily at lower temperatures while maintaining adequate thickness and viscosity when the engine is hot, ensuring that all engine components remain well-lubricated.

Thus, both two-stroke engines and automobiles benefit significantly from the use of multi-viscosity oils, making the choice that includes both categories appropriate. The versatility and performance of these oils are key factors in their applicability in multiple engine types.