What type of engine requires a fuel-oil mix for operation?

A two-stroke engine requires a fuel-oil mix for operation because of its design and the way it functions. In a two-stroke engine, the oil is mixed with the fuel in the gas tank before being fed into the engine. This mixture ensures proper lubrication of the internal components, as two-stroke engines do not have a separate oil reservoir. The fuel-oil mix helps to reduce friction between moving parts and provides adequate lubrication to prevent wear during operation.

In contrast to two-stroke engines, four-stroke engines operate with a dedicated lubrication system that uses oil collected in a separate sump. This oil is circulated through the engine without needing to mix it with the fuel. Similarly, diesel engines also do not require a fuel-oil mix since they use a lubrication system that operates independently of the fuel supply. Turbocharged engines, which can be either two-stroke or four-stroke, attach a turbocharger to enhance performance but do not inherently require a fuel-oil mix unless they are two-stroke types.

Therefore, the need for a fuel-oil mixture is unique to two-stroke engines, making this answer the correct choice.