Why should the lubricant oil be of high viscosity?

Explanation

### Step-by-Step Solution:

1. **Understanding Lubrication**: The primary purpose of lubricating oil is to reduce friction between moving parts in machines. This reduction in friction helps in smoother operation and prevents wear and tear of the components.

2. **Role of Viscosity**: Viscosity is a measure of a fluid's resistance to flow. A lubricant with high viscosity means it is thicker and flows less easily compared to a low viscosity lubricant. High viscosity lubricants can form a thicker film between moving parts.

3. **Effects of Temperature**: The viscosity of lubricating oil can change with temperature. For instance, in summer or at higher temperatures, the viscosity of lubricants tends to decrease. This reduction in viscosity can lead to insufficient lubrication, which may cause parts to come into closer contact and increase friction.

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