One of the key aspects for correct lubricant operation in industry is the control of contamination levels, given that contaminants can lead to increased wear in mechanical systems and accelerated degradation of lubricants. Most of the available filtration techniques focus on removing particles above 4 µm, but not much information is available on the risks of submicron contaminants for lubricant degradation. In this work, a qualitative analysis of the recovered contaminants from a commercial lubricant sample was performed after being treated with different depth filtration methods. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD) were used to observe the contaminants and their composition. Results suggest that conventional depth-filtration systems are not enough to remove submicron contaminants. When combined with other technologies, such as the chemo-mechanical depth filtration system used in this study, the removal of submicron contaminants is enhanced, as seen by the SEM segmentation of the particles present on the analyzed surfaces. Additionally, it is seen that the composition of the contaminant particles is a mixture of wear metals and common additive elements that react and form different oxides and phosphates, which suggest that the interaction between the metal wear particles and the lubricant can have a potential negative impact on the lubricant’s additivation, hence reducing its functionality and service life.