What is "Pour Point", why and when is it important?

 

The pour point is the lowest temperature at which a liquid remains fluid enough to pour. This makes it an important measure for assessing a lubricant's performance in cold conditions; the lower the pour point, the better a lubricant’s fluidity at low temperatures.

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What influences the pour point? It primarily depends on the amount of wax in the base oil. At low temperatures, wax crystals form and then solidify, eventually preventing the lubricant from flowing. A more refined base oil contains less wax, resulting in a lower pour point and better cold-weather performance.

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Now, let's consider how pour point complements viscosity when planning for cold temperatures. Suppose you've adjusted the oil viscosity to suit your application. However, if your operating environment is below 0°C, there's more to consider. For example, imagine your ambient temperature is -10°C, and you've chosen an ISO 32 oil instead of ISO 150 to accommodate the low temperature. However, the Product Data Sheet (PDS) indicates a pour point of -5°C. In this case, you’d need to select a different ISO 32 oil with a lower pour point to ensure reliable performance in those conditions.