Engine oil evaluation through bench testing

This study is the initial step to examine various kinds of bench testing against a set of criteria and to eventually provide guidance for their effective use. Within this context, this paper examines the basic mechanisms of engine oil degradation and deposit formation. Any bench test, to be useful, must simulate some aspects of the basic mechanisms. Various bench test procedures are then described in detail. Bench tests are simple tools used to study a very complex phenomenon, the field test. Because of the enormous expenses and time involved in the field test, engine dynamometer bench tests are developed. In time, these engine bench tests become prohibitively costly, laboratory scale bench tests are used. With each simplification step it is easy to forget the real objective of realistic simulation of field conditions. In simulation tests, the most important question may be what conditions are to be simulated. In a very complex system, the question then becomes what are the key conditions to be duplicated. In engine test simulation, the analysis of used oil and the understanding of the steps or conditions that lead to the final state is essential for successful simulation. Most of the commonly used bench tests, whenmore » evaluated against the engine deposit mechanisms, fail to duplicate most of the conditions. This may, in part, account for the poor reputation of bench tests as a predictive tool in oil performance evaluation. Based on the results and discussions, the following conclusions may be drawn: (1) as a simulation model to predict performance, the existing bench tests are useful but inadequate; (2) properly used, bench tests may be useful in checking consistency of some aspects of oil quality.« less