Farmers are running similar tractor and truck engines on 100% biodiesel because they have a source and the time and space to make into biodiesel. For them it's cheaper. Biodiesel works in the tanks and lines like a solvent. So if everything isn't clean and sludge free it plugs filters. Canadian ferry's had trouble running biodiesel over 50%.
Stay-afloat will seal an open thru hull. Shoring is probably the only way for a temporary fix for loose stringers, better to address in port.