Development of an Engine Test Prediction Model for the Evaluation of Engine Lubricants, Based on Multiple Laboratory Bench Tests

The work presented describes the development of a model for predicting the stability of a lubricant in the Volkswagen PV 1449 engine test (also called VW T4). This engine test is representative of oil drain conditions in engines operating at increased temperatures. In this test the lubricant stability is evaluated by measuring its viscosity increase at the end of the test. That is why two essential performance parameters of the lubricant: 1) oxidation stability, and 2) thermal stability were selected. Using a range of oils having very different performance as evaluated by the engine test, several bench tests were looked at, which are known to evaluate either the oxidation or the thermal stability (or sometimes both) of the oil. Tests were selected based on ranking of the oils and were used to develop a multiple bench test prediction model.

The validity of the model has been demonstrated by comparing the result of VW T4 engine tests, run on a variety of passenger car engine oils containing different additive packages, with the viscosity increase figures calculated by the model. The predicted performance of these oils was in agreement with the viscosity increase given by the engine test. This shows that the model can be used as an efficient screening tool.