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Best Waterproof Marine Grease

Featured image for "Best Waterproof Marine Grease" blog post. Dredging site in ocean.

Water contamination can be a real problem when trying to keep equipment lubricated and protected. Whether the environment is at paper mills, wastewater treatment facilities, large cargo ships, or even boat trailers and recreational boats, keeping water from washing out the lubricant can be a challenge for most conventional general purpose lubricating greases. For the maintenance mechanic, it is best to take stock of the best waterproof marine grease for dealing with water contamination in your specific environment.

How to Find the Best Waterproof Marine Grease

Superior Water Resistance

The first thing to research is how the grease performed during the ASTM D 1264 Water Washout Test @79C. If the grease in question scored less than 0.4% to 0.7% water washout, then this ranks it as a superior grease for water resistance. Many conventional greases claim to be waterproof greases yet their water washout score is 2% to 5%. This may be sufficient for minor or limited exposure to water contamination. For the extreme environments where water is a constant presence, it is suggested that a grease having less than 0.7% water washout be used.

Offshore dredging station.
A 0.4 Water Washout rating would be an important factor to look for when searching for the best waterproof marine grease.







Withstanding Extreme Pressure Shock Loads

Water contamination is not the only issue to consider when choosing a superior water resistant grease. There are other factors that a grease must deal with beyond water contamination to make it an effective grease for protecting critical machinery parts.

For example, if the machine is operating in an environment where water is constantly present, yet at the same time the machine is exposed to extreme pressure and shocks loads, then these constant shock loads can ultimately affect the grease’s water resistance performance along with long term protection during shock loads.

So, we must also consider a grease’s ability to withstand extreme pressure shock loads while being constantly exposed to water contamination. The well known industry test for extreme pressure is called the Timken OK Load Test (ASTM D-2509.) A waterproof grease that scores a 75 to 100 pounds Timken OK Load would be the best choice for extreme pressure conditions. Now that you’ve found a grease with a high Timken OK Load score, the question is can this extreme pressure capability be maintained when the grease is exposed to 20% water? If so, you’ve most likely found the best waterproof marine grease.

Stream excavating crew.
These guys are fishing for a waterproof grease that can withstand shock pressure loads.







When a piece of equipment is exposed to high shock loading and heavy load, it can be said they are functioning at peak or upper level efficiency. There are certain specialty greases on the market that were designed exclusively to score a high Timken OK Load value. Unfortunately, they do not provide the necessary protection from where when the loads are in the more normal range.

In other words, the chemistry is not balanced. It is best when looking at technical data sheets to check the score that the grease rates at during this ASTM D-2266 4 Ball Wear Test. A minimum score  of 0.4 mm to 0.6 mm Scar Diameter illustrates that the grease can protect when loads are more normal.

Offshore excavating crew.
Regardless of the amount of water, a true waterproof grease can protect vital parts.






Withstanding Extreme Operating Temperatures

Another specification that must go hand in hand when choosing a waterproof grease that will be useful in protecting critical machinery parts is the grease’s operating temperature. The first test to look for is the ASTM D-2265 Dropping Point Test. If a grease shows a dropping point “None”, then this could mean that it can withstand higher operating temperatures. It’s a good start. A more realistic higher end operating temperature would be around 440 to 500 degrees Fahrenheit. On the low end or cold operating temperature, a -20 degrees Fahrenheit would be a grease that would not harden up and still have the proper consistency to protect critical machinery parts.

Ocean excavating machinery.
Having to deal with water, mud, etc. is the job of a quality waterproof grease.






Cohesive/Adhesive Properties

The next area to consider would be whether the grease has any cohesive and adhesive characteristics. Having a tacky or stringy consistency would mean the grease would have the capability of providing a tenacious and strong barrier against any damaging contaminants such as dirt, dust, mud, moisture, and water. Also, this tacky or stringy consistency can help during extreme pressure and shock loading, allowing the grease to stay put and protect metal surfaces.

Excavating in mud.
An adhesive and cohesive waterproof grease keeps mud and contaminants out of seals and bearings.










Robust Additive Package

Another area that would help a grease protect against water and other contamination would be what type of additives are used in the formulation. It is important that it have a robust volume of rust and corrosion inhibitors, anti-wear agents, extreme pressure additives, and particularly molybdenum disulfide (MoS 2) or moly.

Utilizing moly adds a protective insurance policy that if the grease lubricating the part were to disappear, then the moly additive would be still plated on the metal surfaces, providing protection until the grease has been replenished. Also, it is important to know that moly can withstand up to 500,000 psi of load.

Close up of moly.
Molybdenum disulfide (MoS2) or moly is a useful lubricant insurance policy.

Superior Rust Prevention

Since the goal is to find a grease that is resistant to water contamination, it is also important to see how effective a grease can be at preventing rust. The industry standard test for rust preventative is the ASTM D-1743. Typical results are rated as follows: 1A is the best or no rust stain. Any result such as 1B, 1C, etc. means there is some rust staining appearing after the test is run. In the case of this article, it is advised that a score of 1A (no rust stain) be the choice.
Heavy machinery near the ocean.
Salt and moisture together are corrosive enemies to equipment. A waterproof grease is the solution.


Overall, an obvious area to investigate is to determine if the waterproof grease can be used in a broad range of applications that encompass load, moisture, heat, impact, etc. Make sure the grease can function properly in areas of application such as U joints, ball bearings, wheel bearings, chassis points, bushings, chains, anti-friction bearings, slides, paper mills, construction equipment, cement plants, logging, trucking, mining, steel mills, water treatment plants, asphalt plants, foundries, automotive, etc. If the grease can protect equipment in all these applications and more, then you’ve found the best waterproof marine grease that is also a multi-purpose lubricant.
Marine drilling station.
A high performance waterproof grease can protect all day in any amount of water.