[Stratofortress]

I see your rationale yet with the usage of EGR, particulate emissions are higher and more soot is formed during combustion and it remains un-oxidized and eventually appears in the exhaust. The rise in smoke (soot) level of engine exhaust due to EGR affects the engine performance in various ways. Increased soot level causes considerable increase in the carbon deposits and wear of the various vital engine parts such as cylinder liner, piston rings, valve train and bearings. Wear of the materials also increase due to chemical reactions taking place on the surface (adsorption, corrosion) or due to abrasion of material or rupture of anti-wear film by soot. The application of EGR also adversely affects the lubricating oil quality and engine durability by the effect of soot interacting with oil additives and thereby reducing its anti-wear properties possibly by abrasive wear mechanism resulting in increased engine wear due to EGR.