Servostern NDH & Servomarine Stern 220 are high quality lubricating oils formulated specially for stern tubes where an emulsifying oil is recommended. These are having special properties to obtain an oil of exceptional lubricating properties with an effective emulsifier. Servostern oils mixes readily with sea water or fresh water to form an emulsion which helps to seal the stern tube against water and maintains a lubricating film within the bearings at all times.