Viscometer for Predicting Low-Temperature Pumpability of Engine Oils

Most engine oils do not have pumpability problems unless used below the engine manufacturers' recommended operating temperatures. An orifice viscometer has been developed which shows promise of identifying the exceptions, those few oils which could have pumpability problems at temperatures above the recommended temperatures. If more extensive testing confirms the initial promise of this method, inclusion of orifice viscometer limits in engine oil specifications would provide consumer protection. The orifice viscometer shows that some oils can be more fluid at a low temperature than at a higher temperature.