Over the last twenty years, the demands on hydraulic oil performance has vastly increased. Hydraulic oil systems have been designed to be smaller, resulting in smaller oil reservoirs. At the same time, hydraulic pumps are now called upon to produce more output, the result being much higher operating pressures. Coupling together these higher pressures along with much smaller oil volume, the end result is much higher oil temperatures. What does this all mean? If the hydraulic oil temperatures rise, this translates to an increase in oxidation, along with the additive chemistry weakened due to extreme temperature increases. What hasn’t changed during these twenty years is the mindset of end users. End users want to invest as little as possible for hydraulic oil that will last as long as possible while simultaneously offering high levels of protection for the machinery.
What would be the hydraulic oil life expectancy? The answer to that question involves many different factors. Some of the common areas that determine the life expectancy of a hydraulic oil would include operating conditions, the quality of the hydraulic oil, and the overall potential for contamination. Your standard above-average hydraulic oil typically has a lifespan of around 6 months under normal operating conditions. If the preventive maintenance program is kept up and the oil is analyzed by a lab consistently, then it is possible to push the hydraulic fluid life expectancy longer.
What factor does oxidation play in hydraulic oil life expectancy? Oxidation typically occurs when temperatures within the hydraulic system go above normal operating conditions. As temperatures rise above a hydraulic oil’s normal operating temperature, the hydrocarbon molecules start to oxidize and start to change to carboxylic acids. As temperatures rise, the rate of oxidation will increase. As the rate of oxidation continues, the quality or the oil’s ability to protect diminishes. This can cause friction, leading to unnecessary metal wear. Over a period of time, this oxidation cycle creates unwanted deposits that can turn into varnish. This varnish can cause critical internal hydraulic parts, such as servo valves, to stick. Beyond varnish, sludge can start to accumulate, which can lead to filters and suction strainers to become clogged. If oxidation were to become severe, the best course of action is to immediately replace the fluid with new hydraulic oil.
Foaming is a common yet problematic issue that can lead to high temperatures and cause performance issues for the machinery. The presence of water in a hydraulic oil can cause foaming. Entrapped air within the hydraulic system can also contribute to foaming issues. Foam acts as an insulation, trapping air within the system. As you can imagine, air is a poor lubricant and if left unchecked can quickly cause hydraulic oil to spiral into an oil that no longer can effectively protect and generate the power it was intended to perform.
If foaming, oxidation, and other contaminants are left unchecked within a hydraulics system, then temperatures will start to rise rapidly. As temperatures rise, critical seals within the hydraulic system will start to degrade and eventually cause hydraulic leaks.
If we factor in all the we’ve discussed so far concerning the myriad of problems that can occur within a hydraulic system, it is easier to understand how hydraulic oil can quickly lose its effectiveness in protecting critical parts. All the factors above cause hydraulic oil life expectancy to become shorter and shorter.
Interestingly, the real question should not be hydraulic oil life expectancy, but rather which hydraulic oil will allow equipment to last the longest and provide the best possible performance. Keeping this concept in mind, let’s consider the use of a specialized hydraulic oil designed and engineered for maximum life expectancy and at the same time providing maximum protection for equipment under the severest conditions. The difference between a conventional hydraulic oil versus a hydraulic oil designed for maximum longevity and equipment protection is the difference between day and night. Where the conventional hydraulic oil, though it meets OEM standards, it still contains the minimum requirements in terms of additive chemistry and conventional base stocks. On the other hand, the high-performance hydraulic fluid we’d like to bring to the reader’s attention is an oil that without a doubt has a very long life expectancy and delivers unparalleled protection and performance for equipment.
Let’s talk about specifics. The custom blended hydraulic oil utilizes new generation base stocks that are super refined with all unwanted byproducts removed, amazing thermal stability, and offers maximum additive integration. When considering today’s extreme demands on hydraulic systems, which operate under much higher temperatures and pressures than in the past, there is a real necessity for an extreme duty hydraulic oil. Such a hydraulic oil will incorporate much higher amounts of zinc than your typical hydraulic fluid. The more zinc, the less wear. Less wear means lower temps. Together, equipment life is extended and oil life is extended.
Another area that a custom blended hydraulic oil excels in is its resistance to any chemical breakdowns. Expect such an oil to be formulated with robust amounts of powerful antioxidant additives. During the Turbine Oil Oxidation Test (ASTM D943), this hydraulic oil scored over 10,000 hours. This is more than 5 times better than what is considered a “good” conventional hydraulic fluid. In other words, such an oil eliminates the potential for oxidation.
Wondering about foam? This high performance hydraulic oil blends in specialized anti-foam chemistry in large quantities. This means that this fluid will release any water or air that could be causing foam. By solving the foaming issue through the use of superior chemistry, you reduce temperatures within the hydraulic system, which leads to longer fluid and equipment life. Another area that directly impacts hydraulic oil life expectancy is any potential for rust formation. Even if moisture is present, a properly formulated hydraulic oil should have corrosion inhibitors that can deal effectively with protecting metal from rust. Again, your top tier hydraulic oil will only use the finest corrosion inhibitors in robust quantities to keep rust in check.
One last area that can contribute to an oil’s life expectancy would be how it operates in cold or hot conditions. Conventional hydraulic oils tend to thicken when exposed to cold temperatures, which can cause hydraulic pumps to cavitate. When temperatures are hot, this same oil tends to thin, leading to fluid loss around the seals. When oil thins, it loses its ability to protect metal, thus accelerating parts wear and creating other unwanted issues. Through the use of the new generation of base stocks that are stable due to their high viscosity index, they exhibit very little viscosity change throughout a wide range of temperatures. Better base stocks, along with high performance chemistry in large volumes, creates an unbeatable package when creating a superior hydraulic oil.
In summary, consider that the most critical area to consider in extending the life of your equipment is through the use of long-lasting, high-performance hydraulic fluid. By opening your field of vision in terms of maximizing the investment in your equipment and the investment in choosing the best possible hydraulic fluid, you gain long life for both areas: the equipment and the fluid.