There are many factors to look at when analyzing the differences of marine grease vs. regular grease. The most popular thickener that is added to the base oil to create a grease would be lithium soaps. Most conventional marine greases and regular grease are made up of lithium soaps. Added to the formulation for those greases would be your standard additives for extreme pressure, rust and corrosion, and additives that can enhance the grease’s ability to deal with water. Again, we’re talking about your conventional, run-of-the-mill marine grease and regular grease. Lithium soaps do not perform naturally well in wet environments. To make them perform better, they require specialized additives. The end result is a grease that is a compromise between regular performance and those needs for moisture resistance.
When creating a custom blended grease specifically for marine use or any application where there will be more than normal exposure to water, there are better thickeners to use beyond lithium soaps. For example, an aluminum complex grease is more water resistant than a lithium soap. The ultimate choice would be a thickener that contains calcium sulfonate soaps. They are much more water resistant and are also considered an anti-corrosion agent. Let’s take a look at a specific test.
The industry standard test to determine a grease’s ability in being resistant to water exposure is the ASTM D-1264 Water Washout @79 degrees C. Most regular greases typically have a water washout of 20% or more when put through this test. Regular greases that are formulated to be more water resistant score on average 7% to 10%. Now, let’s look at a very unique formulation for a grease specifically designed with the ultimate water resistance for marine use. Putting this grease through the ASTM Water Washout Test, it scores a 0.65% rating, a rather extraordinary difference between so-called regular water resistant greases. On further inspection, this grease uses calcium and other thickeners that contribute to this superior water resistant score.
Additionally, the manufacturer of this grease says that even in the presence of up to 20% water, it will retain all its grease functions and retain its extreme pressure protection capabilities. This grease’s ability to withstand large volumes of water and still maintain its extreme pressure capabilities is another example of the vast differences when comparing marine grease vs. regular grease. Regular grease quickly loses most of its lubricating abilities in the presence of water, especially its loss in dealing with extreme pressure or shock loads. What this means is there are consequences to consider beyond just a grease’s ability to withstand moisture and water. If the grease is unable to resist water, then in a very short time, most of its lubricating qualities will be washed away. The result will be excessive parts wear, grease consumption, and ultimately component failure.
Now that we’ve discussed and compared the difference between marine grease vs. regular grease, let’s quickly look at some other performance parameters between the two. We stated before the extreme pressure protection of a grease and how water can affect that. The regular grease used in this comparison was put through the ASTM D-2509 Timken OK Load Extreme Pressure Test. The rating is listed in pounds. This regular lithium-based grease scored a 60 pound Timken OK Load. The marine, or waterproof, grease discussed in this blog post scored a Timken OK Load of 100 pounds. This means it offers far superior ability to resist extreme pressure and shock loads. Please note, as far as we know, there are no regular greases, conventional greases, or major brand greases that can score 100 pounds Timken OK Load. Referring back to the mention of this grease being exposed to 20% volume of water, it still was able to score 100 pounds Timken OK Load. A regular grease that is not specifically formulated for water resistance would score a much lower Timken OK Load if exposed to such high volumes of water.
Another area to compare is oil separation. What do we mean by oil separation? If you observe the inside of a tube of grease that has sitting on the shelf for a period of time, you will notice oil floating on the top or you will notice oil has leaked out onto the shelf. This is oil separation. The oil has literally separated from the thickener. A simple analogy it to open a brand new jar of peanut butter. You will see peanut oil floating on top of the jar. The same thing occurs with conventional, poorly blended greases. Why is this important to know? If the grease’s important lubricating oil is already leaking out while sitting on the shelf, what is going to occur once this grease is put into service? The goal is to have a grease with zero separation. The ASTM D-1742 Oil Separation Test is an industry standard. The regular grease discussed in this article scored a typically average oil separation score of 6%. The calcium-based grease mentioned in this post scored 0.00%. Which grease would you rather use in your vehicle or equipment?
Not only is this grease waterproof, but it is blended to actually provide the necessary lubricating oils for your vehicle or equipment. Another interesting comparison would be a grease’s ability to protect critical parts from wear. The industry standard test is the ASTM D-2266 4 Ball Wear Test D,mm. The lower the number, the less scar, or wear. Test numbers are stated in millimeters(mm.) The lithium grease scored a 0.60 scar mark, the calcium grease was a 0.33 scar mark. The difference between the marine grease vs. regular grease was almost half as much wear. Again, here is another example why utilizing a grease that is water resistant can have a significant impact on multiple performance characteristics of a grease. If a grease is not resistant to water, then all its grease and protection functions are literally washed away, leaving parts exposed and unprotected when in operation. The fact remains, no person or operator can know when vehicles or equipment will be exposed to abnormal amounts of water or moisture. Utilizing a water resistant grease as a general practice makes sense and would be a good investment in protecting your expensive vehicle or equipment.