The Interaction of Lubricant Degradation and Tribology in Automotive Gasoline Engines

(Abstract for STLE Conference, Houston, 2002)

Christopher Hammond, John Lindsay Smith, Moray Stark*, David Waddington
Department of Chemistry, University of York, York YO10 5DD, UK

Richard Gamble, Martin Priest, Christopher Taylor
School of Mechanical Engineering, University of Leeds, Leeds, LS2 9JT, UK

Harold Gillespie, Eiji Nagatomi, Ian Taylor
Shell Global Solutions, Shell Research Ltd, PO Box 1, Chester, CH1 3SH, UK

This work aims is to develop a good understanding of lubricant base fluid degradation in automotive gasoline engines and how this affects engine tribology. Therefore an integrated model has been developed that describes both the lubricant flow within the piston assembly and the chemical degradation of the lubricant.

Experiments with a Ricardo Hydra gasoline engine have been performed using only a hydrocarbon base fluid as lubricant, with no additive package. Oil extraction from the ring pack has allowed the residence time of oil in the ring pack and the flow rate of oil from the sump to the ring pack to be determined; these are compared with oil transport models. The rate of oxidation of the base fluid has been determined by FTIR spectroscopy; the rate of base fluid oxidation compares well with simulations using a chemical model based on detailed free radical chemistry.