Wear Protection Properties of Flexible Fuel Vehicle (FFV) Lubricants

A laboratory wear test is used to evaluate the wear protection properties of new and used engine oils formulated for FFV service. Laboratory-blended mixtures of these oils with methanol and water have also been tested. The test consists of a steel ball rotating against three polished cast iron discs. Oil samples are obtained at periodic intervals from a fleet of 3.0L Taurus vehicles operating under controlled go-stop conditions. To account for the effects of fuel dilution, some oils are tested before and after a stripping procedure to eliminate gasoline, methanol and other volatile components. In addition to TAN and TBN measurements, a capillary electrophoresis technique is used to evaluate the formate content in the oils.

The results suggest that wear properties of used FFV lubricants change significantly with their degree of usage. Wear volume generally increases with length of usage, and correlates well with wear metal analysis of the used oils, and depletion of basicity (as measured by total base number). The high wear and rust formation observed in tests involving some used oils is partially attributed to the high level of formate content in the oils. The test is able to discriminate between candidate lubricants over a 8-month evaluation period.