Lubricant additive effects on engine oil pumpability at low temperatures-detergents and high ethylene olefin copolymer viscosity modifiers

Passenger car and heavy-duty diesel engine manufacturers recognize the need to ensure that engine oils maintain adequate low-temperature pumpability performance throughout their working life. For over two decades, the Mini Rotary Viscometer (MRV TP-1) bench test has been used to develop oils that have protected engines from oil starvation failure during cold weather startup. The test was created to measure the low temperature flow properties of fresh oils. During engine operation, a number of changes take place in the lubricant-both chemical and physical-that can influence oil pumpability. This paper presents a systematic evaluation of the role that various common lubricant additives play in affecting MRV viscosity and pour point and reinforces the notion that new oil MRV is not necessarily a good predictor of used oil pumpability.