Engine oil is mainly comprised of base oils and various additives, which are low molecular weight polymers mixed into the oil resulting in a polymer blend. Dispersants and detergents, the two most abundant additives, are intended to keep the engine free of particulate but are not always successful. At high temperatures, species not combusted may undergo oxidation and degradation or create other byproducts, generating particulate deposition. Knowledge of the molecular makeup of these byproducts is essential, as particulate accumulation can cause serious issues to the engine and ultimately to the operator. In this study, unknown deposits from the air-intake valve of a vehicular engine have been analyzed via a palette of mass spectrometry (MS) methods, including matrix-assisted laser desorption/ionization MS with postacquisition data processing, atmospheric solids analysis probe MS, and electrospray ionization MS interfaced with 2D separation via reversed-phase liquid chromatography and ion mobility spectrometry. Low molecular weight, aminated poly(propylene glycol) and polyisobutylene detergents and a poly(methyl methacrylate) viscosity modifier were conclusively identified in the deposit, along with oxidized polyethylene chains leaked into the oil/additives blend from vehicular tubing and tanks. The use of different methods was essential for the confident elucidation of the low molecular weight macromolecules giving rise to the vehicular engine particulates.