How does increasing oil viscosity benefit an engine in cold conditions?

Increasing oil viscosity in cold conditions provides better lubrication primarily because thicker oil can maintain a protective film around engine components, reducing metal-to-metal contact. In colder temperatures, oil can become too thin, leading to inadequate lubrication when starting the engine. A higher viscosity oil remains more stable and adheres better to engine surfaces, ensuring that there is a sufficient lubricant barrier even when the oil is cold.

The benefit stems from the ability of higher viscosity oils to flow more slowly but maintain a thicker layer between moving parts. This is crucial because, during cold starts, engines are particularly vulnerable to wear, and adequate lubrication helps to minimize this risk as the engine warms up and the oil thins out.

Additionally, while the other options may seem relevant, they do not directly relate to the primary function of oil viscosity in the context of engine operation in cold conditions. For example, reducing engine weight is not associated with oil viscosity; enhancing the engine's appearance does not affect its performance; and decreasing engine stress is a more complex issue that involves many factors beyond just lubrication.