Pour point – lowest flow temperature of a lubricant
The pour point is the lowest temperature at which an oil still flows without solidifying. It is an important parameter in lubricant technology, especially for applications in cold environments or in winter operation. The pour point is measured according to standardized procedures such as ASTM D97.
What does the pour point tell you in practice?
The pour point shows the temperature up to which an engine oil, transmission oil or hydraulic oil can still be pumped – but under stationary conditions. A low pour point is essential for cold engine starts or in industrial operations at sub-zero temperatures to ensure uninterrupted lubrication.
BASINOL lubricants are formulated to combine low pour points with high viscosity stability – for reliable protection even in frost and snow.
How is the pour point measured?
In a laboratory test, the oil is gradually cooled in a glass container. As soon as it stops moving when the container is tilted, the pour point is reached – typically in the range of -9 °C to -60 °C, depending on the type of oil. Important: The value applies under static conditions and is not identical to the limiting pump viscosity.
What is the difference to the limiting pump viscosity?
The pour point shows the theoretical yield point without movement, while the limiting pump viscosity indicates the temperature up to which an oil can practically be pumped through a pump. Therefore, the limiting pump viscosity is often the more realistic value for cold start conditions in the engine, while the pour point is more decisive for storage and system availability in cold conditions.
When is a low pour point particularly important?
In applications with cold starting behavior – e.g. vehicles in Nordic countries, mobile hydraulic systems in winter use or industrial systems in unheated environments – a low pour point protects against oil solidification, starting problems and inadequate lubrication. Modern BASINOL oils with optimized additives and synthetic base oils sometimes achieve pour points of below -50 °C.
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