Low Temperature Starting and Pumpability Requirements of European Automotive Engines

European motor manufacturer replies to the SAE Questionnaire on low temperature starting and pumpability indicate that

• low temperature oil viscosity and flow requirements are primarily determined by engine design.
• CCS viscosities give a useful guide to the cold starting properties of lubricants in European engines.
• there is interest in a classification system temperatures lower than -18°C and oil pumpability.

Experimental test programmes using motored German and French engines confirm that oil pumpability characteristics are largely determined by engine design but show that oil viscosity and VI improver-type additives also have an effect on pumpability. Independent pumpability rig tests show that oil flow rate at -20°C is markedly influenced by the incorporation of an oil filter in the oil circuit.

For both engine and rig tests, the correlation between oil pumpability performance and laboratory test results is investigated.

These studies suggest that, although a standardised rig test to predict oil pumpability may be desirable in the future, there will be considerable difficulty in establishing a procedure which correlates well with the broad range of engine designs currently available in Europe.