True or False: The outer casing of a sealed engine helps keep lubricating fluids in and dirt out.

The statement is true because the outer casing of a sealed engine is specifically designed to serve as a protective barrier that retains lubricating fluids necessary for the engine's operation while preventing contaminants, such as dirt and debris, from infiltrating the engine. This sealing function is critical for maintaining optimal engine performance, as it ensures that the lubricating fluids remain effective in reducing friction and wear among moving parts. A sealed casing helps maintain the integrity and cleanliness of the engine components, which is vital for longevity and efficiency.

While some of the other options introduce conditions or limitations, the fundamental role of the outer casing remains consistently protective across most engine designs, including those not limited to hydraulic systems. Understanding this protective function underscores the importance of maintaining the engine and its components to ensure reliable operation.