The limiting pump viscosity describes the lowest temperature at which an engine oil can still be pumped through the oil pump of an engine without the supply breaking down. It is an important cold weather property value and is measured in millipascal seconds (mPa-s) – the lower this value, the better the oil can be pumped in cold conditions.
What does the limiting pump viscosity say about your oil?
Wear is at its highest during the cold start phase – and it is precisely here that the limiting pump viscosity determines whether the oil reaches all relevant engine components quickly enough. If the oil can no longer be pumped at low temperatures, there is a risk of insufficient lubrication, starting problems and even engine damage.
Modern multigrade oils with low winter viscosity (e.g. 0W-30, 5W-40) are developed in such a way that they flow through the oil ducts even at very low temperatures and supply the engine in seconds. BASINOL engine oils meet the current requirements according to SAE J300 – even in arctic conditions.
At what point does the limit pump viscosity become critical for the engine?
It becomes critical when the temperature drops so low that the oil becomes too viscous to pass through the oil pump and the fine oil channels. It then takes too long for all engine parts to be lubricated – this can lead to increased wear or bearing damage, especially when starting. Oils with a low limiting pump viscosity such as 0W-20 have a clear advantage here.
What is the difference between the limiting pump viscosity and the pour point temperature?
The pour point temperature describes the lowest temperature at which an oil still just flows – but purely under static conditions. The limiting pump viscosity, on the other hand, measures whether the oil can circulate in the engine under realistic pumping conditions. It is therefore the more practically relevant value for the winter suitability of your engine oil.
What is the significance of the limiting pump viscosity in modern vehicles?
Modern engines – especially turbo, hybrid or downsized engines – react sensitively to delayed lubrication when starting. This is why many manufacturers rely on oils with an optimized limiting pump viscosity. Especially for frequent cold starts or in cold regions, an oil such as BASINOL 0W-30 or 5W-40 with very good cold flow properties is a safe choice for maximum engine protection.
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