In what type of small engine is oil mixing with fuel a common practice?

In small engines, the practice of mixing oil with fuel is most commonly associated with 2-stroke cycle engines. This design requires a specific mixture of oil and fuel to lubricate the engine components since it lacks a separate lubrication system like that in 4-stroke engines. In 2-stroke engines, the oil is mixed directly into the fuel to ensure that adequate lubrication reaches the moving parts as the engine cycles. This is essential for the proper functioning and longevity of the engine since 2-stroke engines have a simpler design that relies on the fuel-oil mixture for both combustion and lubrication.

In contrast, 4-stroke engines utilize a dedicated lubrication system that circulates oil to the engine components separately from the fuel. Electric engines don’t have combustion processes that require fuel and oil mixtures, while diesel engines also operate differently, using a specific fuel that doesn't require mixing with oil in the same way as 2-stroke engines. Understanding these distinctions helps clarify why the practice of mixing oil with fuel is unique to 2-stroke cycle engines.