Start-Up Viscosity of In-Service Engine Oils at Low Temperatures

摘要

It has long been established, that the majority of wear that occurs in an engine occurs at start-up. The reason for this is that engine oil normally resides in the crankcase and must be pumped to certain areas of the engine for it to serve its purpose of lubrication. Before the oil is pumped, the engine must be cranked, or started, to engage the oil pump that transfers the engine oil. Out of necessity, the lubricant industry has studied the low- temperature cranking and pumping properties of engine oil. The result has been the creation of an engine oil viscosity classification, SAE J300, which includes requirements for winter viscosity performance. Yet, these requirements are for new engine oils. Limited published research seems to be available with respect to these same oils once they are in service in an engine for an extended amount of time. The goal of this paper will be to evaluate the low-temperature cranking and pumping properties of used engine oils. To evaluate these properties, in-service engine oil samples will be evaluated using the cold cranking simulator and the mini rotary viscometer, because of the vast amount of industry experience with these tests while evaluating oils against SAE J300 classification requirements. These tests will be employed while evaluating numerous used engine oil samples collected from various applications. The big question is whether or not the aging and contamination that engine oils experience dramatically alter low-temperature cranking and pumping properties.