To meet the current and future particulate matter emission standards for gasoline engines is technically challenging even with sophisticated exhaust after-treatment devices. This publication investigates the formation of particulates within the engine using optical diagnostics and fast exhaust gas sampling techniques. In particular, it focuses on the contribution of engine oil to the particulate formation and its concentration in the engine exhaust. The study demonstrates strong correlation between particulates and oil consumption in steady state conditions, at load and thermal transients but also during the official European emission certification cycle.