Tribological response of fresh and used engine oils: The effect of surface texturing, roughness and fuel type

Smooth and rough anisotropic surfaces were used to evaluate the influence of surface roughness and texture on the in situ formation of MoS2 from MoDTC in reciprocating sliding tribotests. In order to also assess the influence of the fuel type contamination (gasoline and ethanol) on the oil properties and tribological performance, the experiments were carried out with an additive free base oil and with a fully formulated 5W30-SM engine oil, as new and after running in dynamometers tests fuelled with ethanol and gasoline. Both texture and fuel types were shown to influence the friction coefficient and wear by changing the tribofilm formation.