The Effect of Gasoline as a Contaminant on the Tribology of Lubricants within the Valve Train System

Requirements within the automotive industry for more efficient fuel economy, performance and lower lubricant consumption have led to less viscous lubricants being produced and applied to automotive engines. This leads to thinner oil films within different lubricant regimes, leading to greater wear of engine components, especially within the valve train system. Contamination of engine lubricants and the oxidation and ageing of the lubricant can have a significant impact on the longevity of the lubricant and engine components. The hybridisation of automotive vehicles and the increasing number of vehicles with stop-start technology causes lower operating temperatures of the combustion engine and increases the risk of fuel contamination in lubricants. Therefore, contamination of lubricants by soot, water, fuel, sand and dust particles has led to greater interest in this research field. Furthermore, industrial stakeholders are focusing on research on engine lubricants to manage their environmental impacts as the performance of engine lubricants affects environmental factors such as exhaust emissions and engine efficiency. This study addresses how engine lubricant contaminants, specifically gasoline contaminant, affect the lubricant's tribology within the valve train system. The study focuses mostly on the interface between the cam and follower to explore how gasoline affects the characteristics of the oil in these interfaces.