Soot is going to be a regular event to deal with in the new (EGR) diesel engine. In the (old) diesel combustion process extra fuel/gases just went out the tail pipe. Diesel fuel is sprayed into the engine via injectors on the compression stroke and does not have time to mix properly with air. The (new) EGR engine will recirculate the exhaust gas back into the cylinder area to (in effect) burn off any left over fuel. Soot, If not adequately dispersed within the oil,begins to agglomerate, or gather into clusters increasing viscosity and allowing deposits to form on metal surfaces. Thick, sooty oil can plug filters and increase operating temperatures which can cause lubrication starvation and ultimately, metal on metal contact. Sandpaper effect...The soot then becomes a harsh abrasive that accelerates wear in cylinder liners, rings, piston skirts, journal bearings and valve trains. Extended Drains might be a thing of the past without::: 1. Bypass filteration which filters soot levels out of oil. 2. Larger sumps and higher quality diesel engine oils. Only time will tell, but it seems at this point the OEM OCI will be the normal...even with synthetics....add to this the new ULSDF and diesel might be in trouble for a few years....any one planning on buying a 2007 diesel engine that wants to be the next (OIL/FILTER EXPERIMENT)for extended drains? Does anyone know what OCI in general will be with the main stream diesels?