Part no: 10021

Sterntube Lubricants delivering superior performance and wear protection even when water ingress occurs

These mineral based lubricants provide an excellent level of lubrication in both neat and emulsion forms. They are developed primarily for use in sterntubes. The products provide:

  • Superior level of lubrication even when water ingress occurs
  • Excellent wear protection
  • Excellent corrosion protection
  • Compatibility with metals commonly used
ISO 9001
ISO 14001

HYDROX 21 is recommended for use particularly where problems of oil leakage past the aft seals is experienced.

HYDROX 21 is compatible with most engine oils and system oils commonly used in the sterntube and can therefore be introduced by top-up procedure to the existing sterntube oil. A minimum of 50% is recommended as the initial charge, however, the lubricant offers the greatest benefit when used to completely fill the sterntube system.


DescriptionMineral oil based sterntube lubricant for use in the event of outboard leakage and with some stabiliser fin shafts.
Typical Viscosity (cSt @40°C)275
Viscosity Index100
Density (kg/ltr@15°C)0.9
Pour Point IP15 (°C)< –5
Anti corrosion SKF Water Emcor TestPasses

HYDROX 21 is compatible with the elastomers used for lip seal systems and are approved by the major lip and face stern seal manufacturers.

HYDROX 21 will absorb any sea or fresh water entering the sterntube to form a fluid emulsion. This reduces the risk of free water being present and continues to provide the required lubrication and corrosion protection. (Conventional oils do not emulsify in the same way and tend to separate, exposing components to free water and potential wear damage).

The emulsions, once formed, have excellent stability, therefore free water is not released. This ensures corrosion protection is maintained even during prolonged standing and during the critical time of start-up.

HYDROX 21 (both neat oil and emulsion including 20% water contamination) has been successfully tested by Class and their stability, lubricating and corrosion protection performance have been verified by Lloyds Register.

Safety Data Sheets (SDS) available to customers

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