Assessment of Correlation Between Bench Wear Test Results and Engine Cylinder Wear, Short-Trip Service

Bench tests are often less expensive and faster than vehicle tests. However, correlation between bench tests and the engine needs to be proven, otherwise bench tests may be misleading. This investigation explored the relationships between bench wear test results and engine results from short-trip driving tests for a variety of conditions: fresh vs. used oil, different methods for assessing wear, and chemical effects such as oil contamination and differences in the fuel. There was a negative correlation between bench tests with fresh oil compared to vehicle test results with used oil, which suggests that bench wear characteristics of fresh engine oil should not be used to determine engine wear rates under the conditions tested here. Statistical analysis of bench test wear rates with used engine oil, compared to engine wear measurements, indicated that the trends were in an appropriate direction, with some scatter in the results. Visual assessment of bench wear surfaces indicated significant differences between one lubricant and another.