Abstract: A multi-stage process for reducing the production of a Product Heavy Marine Fuel Oil from Distressed Fuel Oil Materials (DFOM) involving a pre-treatment process that transforms the DFOM into Feedstock HMFO which is subsequently sent to a Core Process for removing the Environmental Contaminates. The Product Heavy Marine Fuel Oil complies with ISO 8217 for residual marine fuel oils and has a sulfur level has a maximum sulfur content (ISO 14596 or ISO 8754) between the range of 0.05 mass % to 1.0 mass. A process plant for conducting the process is also disclosed.