Soot & Ash (SOA) 100

The composition of soot and ash can be found in section 102. Ash are the unburnable elements of engine oil. As engine oil is consumed the ash elements collect in the cells for the diesel particulate filter (DPF).  Ash is not combustible, it is a byproduct of combustion.

Ash deposits build up slowly at first but increases over time as the engine rings wear and more oil is consumed. The only way to remove ash is to blow it out, dissolve it, or use vibration. The DPF must be removed to clean the ash out of the cells.

Soot consists of the black particles that are left when diesel fuel has not completely combusted. Excess soot burned when using the automatic regeneration system on the engine.

You can plug a DPF with soot very quickly if there are problems with the injector or the fuel is not being efficiently combusted, this will lead to the DPF being overwhelmed and filled with soot within minutes. A regeneration will usually clear excess soot.

Ash takes about 200,000 to 400,000 miles to build-up to the point of needing cleaning. The longer ash is left in the DPF cells the harder it becomes due to excess regenerations and a slight amount of chemicals from coolant.